Chromosomal abnormalities during pregnancy. Chromosomal abnormalities in the fetus: risk factors and diagnosis Chromosomal abnormalities in the fetus are suspected

Identification of a congenital pathology in a child will destroy the happiness of the expectant mother. Chromosomal abnormalities of the fetus can be detected during the initial examination in the 1st trimester of pregnancy: it is important not to miss the optimal timing and follow all the doctor's prescriptions.

The correct set of chromosomes determines the health of the baby

Chromosomal abnormalities of the fetus - what is it

The miracle of the birth of a new life begins with the fusion of two sex cells - a sperm and an egg. The genetic material of the parents, from which a new person is formed, must have a standard set of chromosomes. Any defect of a hereditary or acquired nature can provoke fetal chromosomal abnormalities. This may be an insufficient number or excess of chromosomes, minor violations in individual structures - regardless of the reasons, genetic aberrations become the basis for the pathology of the embryo, which violates the viability of a growing organism.

Causes of intrauterine pathology

The first weeks after conception are the most dangerous time. If fetal chromosomal abnormalities are not associated with genetic defects of the parents, then the causes of intrauterine congenital pathology can be:

1. Aggressive chemicals;
2. X-ray radiation;
3. Ionizing radiation;
4. Toxic and potent drugs;
5. Viral infection.

It is impossible to foresee everything and prevent some external influences on a woman's body, so it is important to strictly follow the doctor's recommendations at the stage of preparation for pregnancy. It is optimal for a married couple planning a conception to visit a doctor for a medical genetic consultation in order to identify the risk of gene defects in future parents. It is necessary to leave hazardous production (chemical enterprises and laboratories, an X-ray room), refuse to take certain medications, and get preventive vaccinations. Some external factors can affect the male and female germ cells long before conception.

Typical types of diseases

Most often, during the initial examination in the 1st trimester, the following fetal chromosomal abnormalities are detected:

1. Edwards disease;
2. Patau syndrome;
3. X-trisomy;
4. Shereshevsky-Turner syndrome.

Typical external defects associated with chromosomal aberrations and detected during examination within 12-13 weeks include:

1. Defect of the skull in the fetus;
2. Skeletal bone anomalies;
3. Malformations in the cardiovascular and genitourinary systems;
4. Craniofascial defects;
5. Mental retardation.

Non-invasive prenatal screening in the form of ultrasound and blood tests will help assess the risk of congenital pathology, invasive examination methods (amniocentesis, cordocentesis) will confirm chromosomal defects in the fetus.

Expectant mother needs to take care of the health of the child in advance

Chromosomal abnormalities of the fetus - what are the possible outcomes

In most cases, nature itself produces natural selection, stopping the development of a non-viable embryo. Chromosomal disorders cause 50-60% (spontaneous abortions up to 8-10 weeks and at least 10% of all cases of intrauterine death of a child). However, congenital defects not detected in time are one of the reasons for the birth of a sick child (0.4% of all births). On average, about 3 thousand children are born annually per 10 million people with various types of congenital and hereditary pathologies. The life expectancy of people with disabilities since childhood is no more than 35 years. No expectant mother wants a sick baby to be born. You would not wish such a fate to any married couple, so it is important to take care of the future ahead of time, following the doctor's recommendations for preconception preparation and

They are called solar children, they bring parents a lot of bright joy and the greatest grief. Children with Down syndrome can be born in absolutely any family. Even if healthy children were born before, there is still a chance that the cells will fail during division, and the karyotype (set of chromosomes) of the newborn will be represented by 47 chromosomes instead of the prescribed 46. In this case, the chromosomes of the last 21st pair will be exactly the same. Hence the name of the diagnosis - trisomy 21. At present, markers of fetal chromosomal pathology allow detecting Down syndrome. In other words, these are signs by which a doctor can predict whether a child will be born healthy or not.

Main types of markers

There are many signs of Down syndrome. It should be noted right away that you should not panic if suddenly the doctor wrote about the presence of one of them. Even if there are several markers, the child is more likely to be born healthy. So, the main physical pathologies of the fetus can be seen on ultrasound. The main symptom is an increase in the collar space. At 10-12 weeks, the width of the neck fold should not exceed 2.5-3 mm. However, if the excess is present, then it's okay. Even if the thickness is about 9 mm, still the probability of having a child with Down syndrome will not be 100%. With slight excesses, the probability of pathology is minimal.

A very common sign of fetal chromosomal pathology, which future mothers are afraid of, is the reverse movement of blood in the umbilical cord. This is indeed a fairly serious violation that can lead to the destruction of the fetus. However, at short stages of pregnancy, reverse blood flow can be detected erroneously. It can pass not along the artery itself, but along the vena cava, where it may well exist without harm to the child. At the same time, with such suspicions, it is worth coming for an examination more often.

External markers of fetal pathology in later pregnancy may be as follows: the presence of a small chin, palpitations, flat bridge of the nose, "Mongolian" epicanthus. Of course, other anomalies that can be determined by experienced doctors also affect the diagnosis. The special shape of the arms, legs, face, neck - all this can be an additional sign of Down syndrome. When examining, you need to pay attention to the presence of an umbilical cord cyst, swelling of the back, and the length of the nasal bones.

As for chemical indicators, doctors traditionally study the level of PAPP-A protein. Normally, in pregnant women, the protein concentration increases, so its low level may indicate the development of Down syndrome and other pathologies.

Ultrasound - the first stage of the examination

An ultrasound examination is performed both at 10-12 weeks and at later stages of pregnancy. Of course, it is mainly aimed at identifying a frozen or ectopic pregnancy. But if, for example, there is a threat of a child with Down syndrome, then the echoscopist focuses on this.

If trisomy is suspected, ultrasound follows a specific plan. First of all, it is revealed whether there is an increase in the thickness of the collar space. Next, the nasal bones of the fetus are analyzed, whether there is a decrease in them. Sometimes nasal bones are completely absent, which is also a marker of chromosomal pathology. The final stage of the external examination is the identification of the facial angle. If it is more than 88.5 degrees, then this also applies to signs of a possible disease.

The second part of the ultrasound examination refers to the examination of the cardiovascular system of the fetus. The venous duct is examined for reverse blood flow, the tricuspid valve of the heart, the presence of various anomalies is revealed. The heart rate is also checked.

Ultrasound examination of pregnant women is done in two ways. The first is classic - it is carried out outside, the peritoneum is checked. The second way is transvaginal. It is quite unpleasant, besides, a woman is obliged to drink about half a liter of water before the examination. The transvaginal method involves invasion through a special vaginal probe. This method is more accurate, for example, it measures the collar space almost perfectly. However, one must understand that any ultrasound may not give a complete picture. For example, because of the umbilical cord wrapped around the neck, measuring the collar zone is absolutely unrealistic. The physique of a woman can be such that the fetus can hardly be seen. In addition, the doctor's experience plays an important role. He must not only be able to take measurements well, but also know the smallest nuances of the structure of the fetus. That is why good doctors always make an appointment a month in advance.

The first ultrasound is usually done at 12 to 13 weeks. It allows you to identify the initial markers of the threat of Down syndrome. The second ultrasound is performed at 20-22 weeks, the third - shortly before childbirth. Usually, an experienced doctor with a probability of up to 70-80% can tell about the presence of chromosomal abnormalities on them.

Biochemical screening

As a rule, doctors refer to biochemical screening a little earlier than ultrasound. This is done precisely because if the screening shows the likelihood of Down syndrome and other abnormalities, then this can be more carefully checked on ultrasound. It should be noted that in some cities of Russia such an analysis is mandatory for all pregnant women. But in some places it is voluntary. Therefore, it is better to do it before the ultrasound.

Biochemical screening involves taking venous blood from a woman for analysis. There is one small but very important condition: you need to do this procedure only from 11 to 13 weeks of pregnancy. After 14 weeks, the significance of the PAPP-A protein for research is significantly lost, and therefore the diagnosis will be very inaccurate.

So how does it all work? The PAPP-A protein is part of a hormone called human chorionic gonadotropin, it is also abbreviated hCG in all documents and certificates. This hormone is the most important indicator during pregnancy. By week 10, the concentration of hCG reaches its maximum. However, an excessively high level of this hormone may indirectly indicate the presence of a chromosomal pathology. And if the level of PAPP-A protein is very low, then the probability of trisomy 21 increases many times over. The lower protein level is 0.5 MoM, and the upper limit of hCG concentration is 2 MoM. Therefore, if these indicators are critically impaired, it's time to check the fetus for ultrasound.

Given that technology is constantly evolving, recent developments have made it possible to release strips for determining hCG and PAPA-A levels in urine. But since the results of these strips are not yet very accurate, large hospitals continue to take blood for tests.

In addition to PAPP-A, biochemical screening may involve the study of other glycoproteins. So, for example, in the second trimester of pregnancy, a high concentration of SP1 glycoprotein can tell about Down syndrome. If for a healthy fetus it is 1 MoM, then for a sick fetus it is 1.28 MoM. However, the increase in SP1 may be due to other factors. The accuracy of diagnosing Down syndrome in this parameter is only 20%.

Inhibin A is a glycoprotein, one of the main markers of chromosomal pathology. He is seen in the first and second trimester of pregnancy. If the concentration of inhibin A is 1.44-1.85 MoM, there is also a high probability of having a child with trisomy 21.

Carrying out calculations

Absolutely any study of markers cannot give an accurate diagnosis. You can only calculate the probability of having a child with chromosomal pathologies. Given that a lot of parameters are being studied, the correct calculation of patterns and probabilities would take doctors a lot of time. Therefore, specialized software is used for calculations. This software calculates the individual risk.

How to interpret the results of marker processing?

If the computer has calculated that the risk of having a child with pathologies is lower than 1:1000, you don’t have to worry too much.

In this case, there is even no point in going for repeated examinations. If the risk is higher, for example, from 1:999 to 1:200, then it is better to do a second biochemical screening in the second trimester, and again at 15-17 weeks to undergo an ultrasound. Again, with average risk indicators, the chances of giving birth to a healthy child still remain maximum. If the risk is 1:100 or higher, for example, 1:10, then pregnancy will have to be given more attention, to undergo the necessary re-examinations.

If the computer has revealed a high probability of pathology, you should once again review the test data yourself. They could simply be entered incorrectly into the computer, and the examinations themselves could be carried out with errors. Considering that doctors work with a huge number of pregnant women, the human factor plays a very important role. Therefore, there is nothing special to be glad that the system showed a small probability of having diabetes in the fetus. There is always risk.

It is worth remembering that examinations prescribed in late pregnancy are less accurate than early ones. If it was not possible to do screening in the interval of 10-14 weeks, then later analyzes by tens of percent reduce the likelihood of detecting anomalies.

The accuracy of the study can also be improved by studying hCG hyperglycosylate, protein S100 and some other markers. In ordinary clinics, such studies are rarely carried out, but in private laboratories and in some places abroad such services are provided. These markers give about 60% accuracy in the detection of DM.

Factors affecting the development of chromosomal pathologies

Of course, biochemical and physical markers of chromosomal pathology make it possible to predict with a high degree of probability the risk of having a child with anomalies. However, women who are just planning to have a child often think about preliminary factors that may affect the development of such abnormalities. There is a very good reason for concern, because according to statistics, 1 child with Down syndrome is born for every 700-800 children.

To a certain extent, heredity influences chromosomal mutations. For example, if the husband had relatives with Down syndrome in the family, the risk increases slightly. Although it is well established that there is no direct transmission of the disease from generation to generation. Moreover, if a married couple gave birth to a sick child, she may well give birth to other healthy children. The risk, of course, increases, but is not absolute. Another interesting pattern is also observed. For example, if one of the identical twins is sick with diabetes, then the other one is also necessarily sick. But if the twins are dizygotic, then, as a rule, only one child is subject to a chromosomal mutation.

Scientists have also found that the risk increases if there is some serious hereditary disease in the family. There is a pattern according to which diabetes mellitus, inherited, increases the risk of having a child with diabetes.

The age of the mother also greatly affects the possible birth of a child with chromosomal abnormalities. Therefore, doctors recommend giving birth to children as early as possible. After age 42, the risk increases many times over. However, they meet newborns with Down's syndrome and in 20-year-old women in labor. The age of the father can also to some extent influence the increase in the likelihood of anomalies. Usually, if the total age of the couple exceeds 70 years, then during pregnancy it is worth undergoing a complete examination for the presence of markers.

Radiation exposure, serious illness during pregnancy, experiences can affect the birth of children with diabetes.

Of course, geneticists cannot establish the exact factors that affect the birth of children with disabilities. And it is unlikely that a woman who sincerely loves a man will refuse to conceive with him because of some kind of genetic disease. But it is quite possible to try to give birth to a child at an earlier age, up to 35 years.

What to do if markers are found and there is a high probability of being born with DM?

Every woman has her own concept of morality and conscience. Statistics show that when conducting ultrasound and biochemical screening, the probability of having a child with Down syndrome can be reduced from 1:800 to 1:1300. This can be achieved by terminating the pregnancy. However, even if several markers indicated a pathology, there is still a possibility that the fetus is healthy. Therefore, terminating a pregnancy, it is quite possible to kill a healthy fetus. If a woman is older, after an abortion, she may never be able to give birth.

In many countries, the identification of markers is aimed at ensuring that the mother can psychologically prepare for the birth of a "sunny" child. Of course, with such children it is much harder than with ordinary ones. However, most families that find themselves in such a situation, although they face difficulties, still call themselves happy and love their child very much, despite the fact that it is not like everyone else. If you work with a child, he may well integrate into ordinary society. Children with Down syndrome make excellent musicians, artists, many of them are really talented. There are cases when people with such a disease lived up to 50-60 years old, worked, had families, even achieved some success. It all depends on the parents, care, how they deal with the child.

There is nothing catastrophic in the birth of a child with such a pathology. But even if all the markers indicate that a child may be born with the disease, there is still a good chance that the predictions are misleading. Children are in any case joy and happiness, no matter what they are born.

Chromosomal diseases or syndromes are a group of congenital pathological conditions manifested by multiple malformations, differing in their clinical picture, often accompanied by severe disorders of mental and somatic development. The main defect is various degrees of intellectual insufficiency, which can be complicated by visual, hearing, and musculoskeletal disorders, more pronounced than an intellectual defect, speech, emotional and behavioral disorders.

Diagnostic signs of chromosomal syndromes can be divided into three groups:

non-specific, i.e. such as severe mental retardation, combined with dysplasia, congenital malformations and craniofacial anomalies;

signs characteristic of individual syndromes;

pathognomonic for a particular syndrome, for example, specific crying in the "cat's cry" syndrome.

Chromosomal diseases do not follow the Mendeleian patterns of transmission of the disease to offspring and in most cases are detected sporadically, as a result of a mutation in the germ cell of one of the parents.

Chromosomal diseases can be inherited if the mutation is present in all cells of the parent organism.

The mechanisms underlying genomic mutations include:

non-disjunction - chromosomes that were supposed to separate during cell division remain connected and belong to the same pole;

"anaphase lag" - the loss of a single chromosome (monosomy) can occur during anaphase, when one chromosome can lag behind the rest;

polyploidization - in each cell the genome is presented more than twice.

Factors that increase the risk of having children with chromosomal diseases

The causes of chromosomal diseases have not been sufficiently studied so far. There are experimental data on the influence on the mutation process of such factors as: the action of ionizing radiation, chemicals, viruses. Other reasons for non-disjunction of chromosomes can be: seasonality, the age of the father and mother, the birth order of children, medication during pregnancy, hormonal disorders, alcoholism, etc. The genetic determination of non-disjunction of chromosomes is not excluded to a certain extent. Let us repeat, however, that the reasons for the formation of genomic and chromosomal mutations at the early stages of embryonic development have not yet been fully elucidated.

Maternal age can be attributed to biological factors that increase the risk of having children with chromosomal abnormalities. The risk of having a sick child increases especially sharply after 35 years. This is characteristic of any chromosomal disease, but is most clearly observed for Down's disease.

In medical genetic planning of pregnancy, two factors are of particular importance - the presence of autosomal aneuploidy in a child and the age of the mother over 35 years.

Karyotypic risk factors in married couples include: aneuploidy (usually in a mosaic form), Robertsonian translocations (fusion of two telocentric chromosomes in the area of ​​division), ring chromosomes, inversions. The degree of increased risk depends on the type of chromosomal disorder.

Down syndrome (trisomy of 21 pairs of chromosomes)

Cause: Non-disjunction of 21 pairs of autosomes, translocation of 21 autosomes to the autosome of group D or G. 94% have a karyotype of 47 chromosomes. The frequency of manifestation of the syndrome increases with the age of the mother.

Clinic: Signs that allow diagnosing the disease, in typical cases, are detected at the earliest stages of a child's life. The small stature of the child, a small round head with a sloping nape, a peculiar face - poor facial expressions, an oblique cut of the eyes with a crease at the inner corner, a nose with a wide flat bridge of the nose, small deformed auricles. The mouth is usually half open, the tongue is thick, clumsy, the lower jaw sometimes protrudes forward. Dry eczema is often noted on the cheeks. Shortening of the limbs is found, especially in the distal sections. The hand is flat, the fingers are wide, short. They lag behind in physical development, but not sharply, but neuropsychic development is slow (speech is poorly developed). With age, a number of new features of the disease are revealed. The voice coarsens, myopia, strabismus, conjunctivitis, abnormal growth of teeth, caries are noted. The immune system is poorly developed, infectious diseases are extremely difficult and 15 times more common than in other children. There is acute leukemia.

Pathogenesis: Pathologies of internal organs, cardiovascular defects.

Diagnostics: Clinical examination confirmed by cytogenetic analysis of the karyotype.

Treatment: Complex therapy, including the correct organization of the regimen, rationally constructed medical and pedagogical work, physiotherapy exercises, massage, drug treatment.

Turner-Shershevsky Syndrome (CS)

Cause: Nondisjunction of sex chromosomes, absence of one X chromosome, karyotype - 45 chromosomes.

Clinic : Short stature, disproportionate body structure, full short neck with pterygoid skin folds, wide chest, X-shaped curvature of the knees. The ears are demorphed, set low. Abnormal growth of teeth is noted. Sexual infantilism. Decreased mental development.

Pathogenesis: During puberty, underdevelopment of the genital organs and secondary sexual characteristics, damage to the vascular system, anomalies of the urinary system, decreased visual acuity, hearing.

Diagnostics : In newborns, it is difficult to establish. With age, the diagnosis is based on the clinical picture and the determination of the pathology of the karyotype and sex chromatin.

Treatment: Symptomatic, aimed at increasing growth. Anabolic hormones are used to increase growth. From the age of 13-15, treatment with estrogenic drugs begins. Complete recovery is not observed, but therapeutic measures can improve the condition

Klinefelter syndrome (XXY; XYY; XYYYY; XXXY)

Cause: Nondisjunction of sex chromosomes, as a result of which the number of X or Y chromosomes in the cell increases, the karyotype is 47 (XXY), 48 or more chromosomes.

Clinic: High growth, lack of bald patches on the forehead, poor beard growth, gynecomastia, osteochondrosis, infertility, underdeveloped muscles, anomalies of the teeth and skeletal system. Patients may demonstrate reduced intelligence. With an increase in X chromosomes, mental retardation increases to complete idiocy, with an increase in Y chromosomes - aggressiveness. Patients with a deeper degree of intellectual defect may show a number of psychopathological signs: they are suspicious, prone to alcoholism, capable of committing various offenses.

Pathogenesis: In the pubertal period, underdevelopment of primary sexual characteristics is found.

Diagnostics: Based on clinical data, as well as on the determination of the pathological karyotype by the cytogenetic method, which is confirmed by the study of sex chromatin in cells.

Treatment: Therapy with male sex hormones to increase potency. Psychotherapy.

Wolf-Hirshhorn syndrome

Cause: In 80% of newborns suffering from it, the cytological basis of this syndrome is the division of the short arm of the 4th chromosome. The size of the deletion ranges from small terminal to occupying about half of the distal part of the short arm. It is noted that most of the deletion occurs again, about 13% occurs as a result of translocations in the parents. Less commonly, in the genome of patients, in addition to translocation, there are also ring chromosomes. Along with divisions of chromosomes, pathology in newborns can be caused by inversions, duplications, isochromosomes.

Clinic: Newborns have a small weight with a normal duration of pregnancy. Microcephaly, coracoid nose, epicanthus, anti-Mongoloid incision of the eyes (omission of the outer corners of the eye fissures), abnormal auricles, cleft lip and palate, small mouth, deformity of the feet, etc. are also noted. Children with Wolff-Hirschhorn syndrome are not viable, usually die in under the age of one year.

Pathogenesis: The disease is characterized by numerous congenital malformations, mental retardation and psychomotor development.

Diagnostics: According to the clinical picture.

Treatment: Does not exist.

trisomy syndrome (XXX)

Cause: Nondisjunction of sex chromosomes as a result of disruption of the mitotic spindle during meiosis, karyotype - 47 chromosomes.

Clinic: Vesical non-disjunction of the placenta; the newborn has a small, wide posterior fontanel, underdeveloped occipital and parietal bones of the skull. Lag in development for 6-7 months. Deformed auricles are located low. Syndactyly of the fingers, cleft lip and palate, hydrocephalus. Many women are normally developed, intelligence is below average. The frequency of development of schizophrenia-like psychoses increases second.

Pathogenesis: Malformations of internal organs.

Diagnostics: According to the clinical picture and cytogenetic definition of the pathology of the karyotype and sex chromatin.

Treatment: Symptomatic.

Edwards syndrome (trisomy of chromosome 18)

Cause: Nondisjunction of autosomes at the stage of gametes (sometimes zygotes). Extra chromosome in the 18th pair. Karyotype 47, E18+. The dependence of the frequency of birth of sick children on the age of the parents is expressed.

Clinic: Prenatal underdevelopment, weak fetal activity, facial structure disorders (short palpebral fissures, small upper jaw) and the musculoskeletal system are almost constant. The auricles are deformed and in the vast majority of cases are located low. The sternum is short, the ossification nuclei are located incorrectly and in smaller numbers. Spinal hernias and cleft lips.

Pathogenesis: The most permanent defects of the heart and large vessels. Developmental disorders of the brain, mainly hypoplasia of the cerebellum and corpus callosum. Of the defects of the eyes, microanaphtholmia is most often detected. Congenital absence of the thyroid gland and adrenal glands.

Diagnostics: Clinical examination, dermatoglyphics,

cytogenetic examination.

Treatment: Absent, 90% of children die in the first year of life. Surviving children die from infectious diseases, more often from pneumonia.

Patau syndrome (trisomy but 13 autosomes)

Cause: Nondisjunction of autosomes of the 13th pair in gametogenesis in one of the parents. Karyotype - 47, D13+.

Clinic: Anomalies of the skull and face, the circumference of the skull is usually reduced, in some cases there is a pronounced trigonocephaly. Moderate microcephaly is combined with a relatively low and sloping forehead, narrow palpebral fissures, a sunken forearm with a wide nasal base, and low-lying and deformed auricles. The distance between the palpebral fissures is often reduced. The scalp has oval or round shaped scalp defects. Often - cleft lip and cleft palate. Anomalies of the musculoskeletal system, polydactyly.

Pathogenesis: Mortality during the first year of life (90%). The main cause of death in children are severe, incompatible with life malformations: defects in the cardiovascular and genitourinary systems, anomalies of the large intestine, umbilical hernia, disorders of the structure of the eyeballs, constant microanophthalmia, retinal dysplasia, cataracts. Congenital heart defects occur in 80% of children.

Diagnostics: Based on clinical, cytogenetic studies.

Syndrome "cat's cry"

Cause: Deletion of the short arm of chromosome 5. Karyotype 46, 5p-.

Clinic: Pathological structure of the vocal cords - narrowing, softness of the cartilage, swelling and unusual folding of the mucosa, meowing of a cat. Underdevelopment of speech. Microcephaly. Moon-shaped face, Mongoloid eyes, strabismus, cataract, optic nerve atrophy, flat nasal bridge, high palate, deformed auricles. Clubfoot. Delayed mental and physical development. Life expectancy is significantly reduced, with only about 14% of patients surviving the age of 10 years.

Pathogenesis: Heart disease.

Diagnostics: Clinical examination with the identification of the most constant sign of the syndrome - "cat's cry", dermatoglyphics and cytogenetic detection of karyotype pathology.

Treatment: Absent.

Orbeli syndrome

Cause : Divisions of the long arm of the autosome 13.

Clinic: The forehead passes into the nose without forming a nasal notch. Large distance between eyes. Wide back of the nose, high palate, low-lying dysplastic auricles, malformations of the eyes (strabismus, cataracts). Defects of the musculoskeletal system - nonspecific anomalies (clubfoot, dislocation of the hip joints). growth retardation and psychomotor development; characterized by profound oligophrenia. Patients with a detailed clinical picture of the syndrome die in the first year of life.

Pathogenesis: Abnormal development of almost all organs and systems; microcephaly; congenital heart defects and anomalies of the rectum.

Diagnostics:

Treatment: Absent.

Maurice syndrome

Cause: A gene mutation that disrupts the formation of a normal receptor protein makes target tissues resistant to the hormone that directs their development in the male pattern. Without using this opportunity at a certain stage of ontogenesis, the organism develops according to the female type.

Clinic: An individual with the XY karyotype appears, but outwardly it is more similar to a woman. Such subjects are not able to have offspring, since their sex glands (testes) are underdeveloped, and their excretory ducts are often formed according to the female type (underdeveloped uterus, vagina). Secondary sexual characteristics are also characteristic of the female.

Pathogenesis: Underdeveloped genitals.

Diagnostics: Cytogenetic, clinical examination.

Treatment: hormone therapy.

The normal course of pregnancy and the excellent health of a young woman is not yet a guarantee of the birth of a healthy child without anomalies. It is important even in the early stages of pregnancy to carry out the necessary diagnostic measures to identify or exclude chromosomal pathology. Anomalies of intrauterine development can be provoked by environmental factors, heredity, the condition of the mother, and other less common causes.

What is a chromosomal anomaly? This is the appearance during fetal development of an extra chromosome or a violation of its structure. Everyone is familiar with Down syndrome, so this congenital disease is associated with an extra chromosome in the 21st pair. It is possible to identify this pathology even before birth due to the clinical picture, characteristic diagnostic signs, and the nature of the course of pregnancy.

Signs of chromosomal abnormality during pregnancy

Anomaly of chromosomes happens quite often in a child who was affected by adverse factors during fetal development. This applies to a woman's lifestyle, her state of health, and the environment.

Congenital pathologies, including an extra 21 chromosome, can be suspected by the following signs:

• pulling pains in the lower abdomen throughout the entire period of pregnancy, the threat of miscarriage;
• decreased fetal activity, increased fetal kidneys at 20-21-22 weeks;
• underdevelopment of the tubular bones of the fetus;
• underdevelopment of the placenta, fetal hypoxia;
• polyhydramnios or oligohydramnios.

These concomitant manifestations of pregnancy may indicate an anomaly, but an analysis is needed to confirm, since each of the presented pregnancy abnormalities may indicate other disorders, and in some cases even be the norm. But why does a chromosomal failure happen and is it possible to prevent it?

Causes of chromosomal abnormalities

Late pregnancy is a risk factor

Risk factors in the development of congenital anomalies are too diverse and it is physically impossible to follow all the components. This is an environmental factor that cannot be influenced, and problems that arise even in the process of fertilization, when during the connection of 46 chromosomes an abnormal appearance or disappearance of another chromosome occurs. The process is quite complex, and it is impossible to trace it from the very beginning, that is, from the moment of conception.

The most common pathology is the appearance of an extra chromosome 21, one of the varieties of trisomy, when the chromosome has three copies. For example, people with Down syndrome have three copies of chromosome 21.

It often happens that a fetus with a chromosomal abnormality does not survive, a miscarriage occurs in the early stages. But those who survive are born with serious problems, both physical and mental.

Diagnosis of chromosomal abnormalities

Today, it is not a problem to detect an extra 21 chromosome before birth, as well as other abnormalities. For this purpose, an analysis of the chromosome set is carried out, by taking blood after the birth of a child or by examining the chorion. Cells that were obtained through a biopsy are grown in a laboratory, after which they are analyzed for the presence of an extra chromosome 21 or the absence of some chromosomes of the set.

Geneticists recommend conducting this analysis for every woman in order to know for sure the possibility of a chromosomal pathology in an unborn child. This analysis can be carried out regardless of the woman's age and gestational age, but the efficiency of the analysis is high and in 99% it is possible to conduct an accurate analysis of the chromosome set.

The first stage of diagnosis begins with a mother's blood sampling in the first trimester of pregnancy, and an ultrasound examination is also performed to visually examine the fetal neck, which is of diagnostic importance in suspecting an extra chromosome 21 - Down syndrome. In the second trimester of pregnancy, a mother's blood test is also performed, during this period the greatest risk of a chromosomal abnormality can be determined.

Women who are at risk should undergo an additional analysis - a chorea biopsy is performed to make a diagnosis.

Frequent chromosomal abnormalities

The first place is occupied by trisomy 21 chromosomes - Down syndrome. This congenital disease is diagnosed in 1 in 700 babies. Such children are mentally retarded, have specific external signs, characteristic facial features and are more prone to systemic diseases than healthy children.

Children with Down syndrome have limited intellectual potential, but at the present stage, activities are being carried out aimed at the socialization of such children, they can further learn and engage in activities that do not require serious physical and intellectual demands. Early intervention by psychologists, psychotherapists and other specialists can improve the prognosis for the development of children with an extra 21 chromosome, they begin to write, read and take an active part in collective activities.

The risk of having a child with a chromosomal pathology increases in proportion to the age of the mother. So, women under 25 give birth to a child with a chromosomal disorder 1 out of 15,000, and women after 45 years - 1 out of 40. The difference is significant, and therefore older age remains the main risk group.

The second most common anomaly is trisomy 13 and 18 chromosomes - these abnormalities are much more serious than Down's syndrome, and very often such children do not survive. If a woman was analyzed and the result showed these anomalies, the doctor will suggest an abortion at an early stage of pregnancy, since the chances of enduring and giving birth are minimal.

Children born with trisomy 13 - Patau syndrome and trisomy 18 - Edwards syndrome suffer from serious physical and mental disabilities. Each child has a pronounced external developmental defect, and they live no more than a year.

Anomalies of sex chromosomes - Turner's syndrome, trisomy on the X chromosome, Klinefelter's syndrome and disomy on the Y chromosome occur when there are violations of 23 pairs of chromosomes.

Turner syndrome - occurs in 1 in 3,000 girls born. Such girls do not go through puberty, they lack the second X chromosome, they are infertile. Such girls stop growing early if hormone therapy is not started from an early age. Adequate hormonal treatment can only partially restore sexual function, but they cannot return the possibility of having a child with any drugs.

Other chromosomal pathologies associated with a violation of the 23rd pair of chromosomes occur very rarely, and all those born with this anomaly have no reproductive function.

Rare chromosomal abnormalities

Some chromosomal anomalies are so rare that their analysis does not show at all or shows, but a completely different violation. These include deletion, inversion, translocation, circular chromosome and microdeletion. This is a series of disorders in the chromosomal series that develop due to diseases on the part of the mother.

Rare chromosomal pathologies can occur against the background of maternal diabetes, diseases of the endocrine system, smoking and other bad habits. Every woman after 35 years of age is analyzed to determine chromosomal abnormalities, as well as girls under 16 years old. Of great importance is the course of pregnancy, past infectious diseases, intrauterine infections or toxic effects on the fetus.

• Essence of diseases
• Causes
• signs
• Diagnostic methods
• Deciphering and calculating risks
• Forecasts
• Diseases

During pregnancy, various tests and studies can diagnose fetal chromosomal abnormalities, which are inherently hereditary diseases. They are due to changes in the structure or number of chromosomes, which explains their name.

The main cause of occurrence is mutations in the germ cells of the mother or father. Of these, only 3-5% are inherited. Due to such deviations, about 50% of abortions and 7% of stillbirths occur. Since these are serious gene defects, throughout pregnancy, parents should be more careful about all prescribed tests, especially if they are at risk.

Essence of diseases

If the parents (both) have hereditary diseases in the family, they first need to know what it is - fetal chromosomal pathologies that can be detected in their child while he is still in the womb. Awareness will help to avoid unwanted conception, and if this has already happened, to eliminate the most serious consequences, ranging from the death of a baby in utero and ending with external mutations and deformities after his birth.

In a normal, healthy person, chromosomes line up in 23 pairs, and each pair is responsible for a specific gene. In total, 46 are obtained. If their number or structure is different, they speak of chromosomal pathologies, of which there are a lot of varieties in genetics. And each of them entails dangerous consequences for the life and health of the baby. The main causes of this kind of anomaly are unknown, but there are certain risk groups.

With the world on a string. One of the rarest chromosomal abnormalities is called crying cat syndrome. The reason is a mutation of the 5th chromosome. The disease manifests itself in the form of mental retardation and the characteristic crying of a child, which is very reminiscent of a cat's cry.

Causes

In order to prevent or recognize fetal chromosomal pathologies in time during pregnancy, doctors should interview future parents about hereditary diseases and the living conditions of their family. According to recent studies, gene mutations depend on this.

There is a certain risk group, which includes:

• the age of parents (both) is over 35 years;
• the presence of HA (chromosomal abnormalities) in blood relatives;
• harmful working conditions;
• long-term residence in an ecologically unfavorable area.

In all these cases, there is a fairly high risk of fetal chromosomal pathology, especially in the presence of hereditary diseases at the gene level. If these data are detected in a timely manner, doctors are unlikely to advise the couple to give birth at all. If conception has already occurred, the degree of damage to the child, his chances of survival and further full life will be determined.

Origin mechanism. Chromosomal pathologies develop in the fetus when a zygote is formed and the sperm and egg merge. This process is not controllable, because it is still little studied.

signs

Since the process of occurrence and development of this kind of abnormalities has not been sufficiently studied, markers of fetal chromosomal pathology are considered conditional. These include:

• the threat of miscarriage, pulling pains in the lower abdomen in the early stages of pregnancy;
• low level of PAPP-A (plasma protein A) and AFP (a protein produced by the body of the embryo), elevated hCG (chorionic gonadotropin - placental hormone): to obtain such data, blood is taken from a vein for fetal chromosomal pathology for a period of 12 weeks (+/ - 1-2 weeks);
• the length of the nasal bones;
• enlarged neck fold;
• fetal inactivity;
• enlarged renal pelvis;
• slow growth of tubular bones;
• earlier aging or hypoplasia of the placenta;
• fetal hypoxia;
• poor results of dopplerometry (ultrasound method for detecting circulatory pathologies) and CTG (cardiotocography);
• little and polyhydramnios;
• hyperechoic intestine;
• small size of the maxillary bone;
• enlarged bladder;
• cysts in the brain;
• swelling in the back and neck;
• hydronephrosis;
• facial deformities;
• umbilical cord cysts.

The ambiguity of these signs is that each of them individually, like the entire complex listed above, can be the norm, due to the individual characteristics of the body of the mother or child. The most accurate and reliable data are usually given by a blood test for chromosomal pathologies, ultrasound and invasive techniques.

through the pages of history. By examining the chromosomes of modern humans, scientists found that they all got their DNA from one woman who lived somewhere in Africa 200,000 years ago.

Diagnostic methods

The most informative method for diagnosing fetal chromosomal pathologies is the first screening (it is also called a double test). Do at 12 weeks pregnant. It includes:

• Ultrasound (markers indicated above are detected);
• a blood test (taken from a vein on an empty stomach) showing the level of AFP, hCG, APP-A.

It should be understood that this analysis for fetal chromosomal pathologies cannot give an accurate, 100% confirmation or refutation of the presence of anomalies. The task of the doctor at this stage is to calculate the risks, which depend on the results of the studies, the age and medical history of the young mother. The second screening (triple test) is even less informative. The most accurate diagnosis is invasive methods:

• chorion biopsy;
• cord blood sampling;
• amniotic fluid analysis.

The purpose of all these studies is to determine the karyotype (a set of features of a set of chromosomes) and, in connection with this, chromosomal pathology. In this case, the accuracy of diagnosis is up to 98%, while the risk of miscarriage is no more than 2%. How is the decoding of the data obtained in the course of these diagnostic techniques?

Ultrasound and risks to the fetus. Contrary to the widespread myth about the dangers of ultrasound for the fetus, modern equipment makes it possible to reduce the negative impact of ultrasound waves on the baby to zero. So do not be afraid of this diagnosis.

Deciphering and calculating risks

After the first double screening is done, ultrasound markers of fetal chromosomal pathology that were identified during the study are analyzed. Based on them, it calculates the risk of developing genetic abnormalities. The very first sign is an abnormal size of the collar space in an unborn child.

Ultrasonic markers

Absolutely all ultrasound markers of fetal chromosomal pathology of the 1st trimester are taken into account in order to make the necessary calculations of possible risks. After that, the clinical picture is supplemented by a blood test.

Blood markers

All other indicators are considered deviations from the norm.

In the second trimester, inhibin A, unconjugated estriol and placental lactogen are also evaluated. All decoding of the results of the research carried out is carried out by a special computer program. Parents can see the following values ​​as a result:

• 1 in 100 - means that the risk of genetic defects in the baby is very high;
• 1 in 1000 is the threshold risk of fetal chromosomal pathology, which is considered normal, but a slightly underestimated value may indicate the presence of some kind of anomaly;
• 1 in 100,000 is a low risk of fetal chromosomal pathology, so you should not be afraid for the health of the baby from the point of view of genetics.

After the doctors calculate the risk of chromosomal pathology in the fetus, either additional studies are prescribed (if the value obtained is lower than 1 in 400), or the woman calmly nurses the pregnancy to a successful outcome.

It's curious! The male Y chromosome is the smallest of all. But it is she who is transmitted from father to son, preserving the continuity of generations.

Forecasts

Parents whose child was found to have chromosomal pathologies in utero should understand and accept as a given that they are not being treated. All that medicine can offer them in this case is an artificial termination of pregnancy. Before making such a responsible decision, you need to consult with doctors on the following issues:

• What kind of pathology was diagnosed?
• What consequences will it have for the life and health of the child?
• Is there a risk of miscarriage and stillbirth?
• How old do children live with this diagnosis?
• Are you ready to become the parent of a disabled child?

To make the right decision about whether to leave a sick baby or not, you need to objectively evaluate all the possible consequences and results of the fetal chromosomal pathology together with the doctor. In many ways, they depend on what kind of genetic anomaly doctors suggest. After all, there are enough of them.

Curious fact. Patients with Down's syndrome are usually called sunny people. They are rarely aggressive, most often very friendly, sociable, smiling and even talented in some ways.

Diseases

The consequences of chromosomal pathologies detected in the fetus can be very different: from external deformities to CNS damage. In many ways, they depend on what kind of anomaly occurred with the chromosomes: their number has changed or mutations have affected their structure. Among the most common diseases are the following.

Violation of the number of chromosomes

• Down syndrome is a pathology of the 21st pair of chromosomes, in which there are three chromosomes instead of two; accordingly, such people have 47 instead of the normal 46; typical signs: dementia, delayed physical development, flat face, short limbs, open mouth, strabismus, bulging eyes;
• Patau syndrome - violations in the 13th chromosome, a very severe pathology, as a result of which numerous malformations are diagnosed in newborns, including idiocy, multi-fingeredness, deafness, mutations of the genital organs; such children rarely live to a year;
• Edwards syndrome - problems with the 18th chromosome, often associated with the advanced age of the mother; babies are born with a small lower jaw and mouth, narrow and short palpebral fissures, deformed ears; 60% of sick babies die before 3 months, and 10% live up to a year, the main causes of death are respiratory arrest and heart defects.

Violation of the number of sex chromosomes

• Shereshevsky-Turner syndrome - abnormal formation of the gonads (most often in girls), due to the absence or defects of the sex X chromosome; among the symptoms - sexual infantilism, skin folds on the neck, deformity of the elbow joints; children with such a chromosomal pathology survive, although childbirth is very difficult, and in the future, with proper supportive treatment, women can even bear their own baby (through IVF);
• polysomy on the X or Y chromosome - a variety of chromosomal disorders, characterized by a decrease in intelligence, an increased likelihood of developing schizophrenia and psychosis;
• Klinefelter's syndrome - disorders of the X chromosomes in boys, who in most cases survive after childbirth, but have a specific appearance: lack of vegetation on the body, infertility, sexual infantilism, mental retardation (not always).

Polyploidy

• such a chromosomal pathology in the fetus always ends in death even before birth.

Why gene mutations occur at the chromosome level, scientists are still trying to find out. However, this is still only a matter of the future, and at this point in time, chromosomal pathologies detected in utero in the fetus account for up to 5% of all cases.

What should parents do when they hear such a diagnosis? Do not panic, reconcile, listen to the doctors and make the right decision together with them - to leave a sick baby or agree to an artificial termination of pregnancy.

Under congenital anomalies implies the pathology of the development of the embryo from the moment of fertilization to the onset of childbirth, and, depending on the timing of its occurrence, the following forms are distinguished: hereditary diseases), blastopathy (damage to the zygote in the first two weeks after fertilization, leading to the death of the embryo, ectopic pregnancy, congenital malformations), embryopathy (damage to the embryo from 15 days after fertilization to the formation of the placenta - 75 days, congenital malformations may occur individual organs and systems, termination of pregnancy), fetopathy (a pathology that occurs from day 76 until birth, manifested by intrauterine growth retardation, congenital malformations, preservation of the original location of organs, underdevelopment of organs, congenital diseases, as well as premature birth, asphyxia at birth) .

Causes of malformations.

These reasons are very varied. But most often these are diseases of the mother of various organs and systems, endocrine pathologies, infectious diseases, both chronic and existing before pregnancy, and those that developed during pregnancy; obstetric and gynecological pathology of the mother (abortions that were before pregnancy, long-term threats of abortion, especially in the early stages, prolonged or severe toxicosis, and others). Also, a huge role is played by environmental factors and other harmful effects on the body of a pregnant woman and the fetus: physical (various radiation, temperature), chemical (industrial and household chemicals, drugs - more about them below, alcohol, nicotine and other drugs), biological factors (infection and their toxins). The role of hereditary factors (various chromosomal aberrations and gene mutations) is also great. It should also be noted the especially important role of a balanced diet without a deficiency of not only the main food ingredients (proteins, fats, carbohydrates, minerals, vitamins), but also micronutrients (microelements, polyunsaturated omega fatty acids and others) both during pregnancy and at the time of pregnancy. pregnancy planning. For example, iodine deficiency in a woman before conception and in early pregnancy can lead to fetal hypothyroidism, brain development disorders. Risk factors and possible pathology of newborns, on the part of the mother:

• age over 35 years - chromosomal abnormalities, intrauterine growth retardation;
• age under 16 - prematurity;
• low socio-economic status - prematurity, intrauterine growth retardation, infections;
• folic acid deficiency - congenital malformations;
• smoking - intrauterine growth retardation, increased prenatal mortality;
• alcohol or drug use - intrauterine growth retardation, fetal alcohol syndrome, withdrawal syndrome, sudden death syndrome;
• diabetes mellitus - stillbirth, large body weight, congenital malformations;
• thyroid diseases - goiter, hypothyroidism, thyrotoxicosis;
• kidney disease - intrauterine growth retardation, stillbirth, nephropathy;
• diseases of the lungs and heart - intrauterine growth retardation, prematurity, congenital heart defects;
• arterial hypertension - intrauterine growth retardation, asphyxia;
• anemia - intrauterine growth retardation, stillbirth;
• polyhydramnios - congenital malformations of the kidneys, central nervous system, gastrointestinal tract;
• low levels of estriol in the urine - intrauterine growth retardation;
• bleeding - prematurity, stillbirth, anemia;
• infections, especially toxoplasmosis, rubella, herpes - intrauterine growth retardation, congenital malformations, encephalopathy, pneumonia.

From the side of the fetus:

• multiple pregnancy - prematurity, fetofetal transfusion, asphyxia;
• intrauterine growth retardation - asphyxia, stillbirth, congenital malformations;
• anomalies of fetal presentation - trauma, hemorrhage, congenital malformations.

• premature birth - asphyxia;
• delayed birth (for 2 or more weeks) - stillbirth, asphyxia;
• prolonged childbirth - stillbirth, asphyxia;
• prolapse of the umbilical cord - asphyxia.

Anomalies of the placenta:

• small placenta - intrauterine growth retardation;
• large placenta - dropsy of the fetus, heart failure;
• premature detachment of the placenta - blood loss, anemia;
• placenta previa - blood loss, anemia.

The effect on the fetus and newborn of drugs used by a woman during pregnancy:

aloe enhances intestinal peristalsis, aminoglycosides (streptomycin, gentamicin, kanamycin and others) have a toxic effect on the ear and kidneys, androgens cause various malformations, antihistamines lower blood pressure, cause tremors, indirect anticoagulants cause nasal hypoplasia, disrupt fetal bone formation, can cause encephalopathy , atropine depresses respiration, barbiturates can cause minor cerebral dysfunction, belladonna drugs - tachycardia, blood pressure lowering drugs - impair blood flow between the child and the placenta, diazepam - muscle hypotension, hypothermia, apnea, cleft lip and nose, isoniazid - convulsions, indomethacin - pulmonary hypertension, premature closure of the ductus arteriosus, corticosteroids - encephalopathy, fetal adrenal suppression, caffeine - liver damage, xanthines - tachycardia, lithium - lethargy, congenital heart defects, burnt magnesia - kidney damage, nitrofurans - hemolysis of erythrocytes, obzidan - prolongation of labor, opiates - depress breathing, minor brain dysfunction, anticonvulsants - intrauterine growth retardation, malformations, reserpine disrupts nasal breathing, salicylates - bleeding, seduxen causes respiratory depression, lowers blood pressure, theophylline - disrupts blood clotting, phenothiazines - muscle hypotension, tetracyclines - multiple bone anomalies and skeleton. Possible malformations, depending on the time of exposure to the above factors:

• in the third week of pregnancy, the fetus may develop ectopia of the heart, hernia of the umbilical cord, congenital absence of limbs, fusion of the feet;
• in the fourth week from the moment of fertilization, a hernia of the umbilical cord, congenital absence of feet, tracheoesophageal fistula, hemivertebra may appear;
• at the fifth week of development - tracheoesophageal fistula, hemivertebra, central cataract, microphthalmia, splitting of facial bones, absence of a hand and foot;
• at the sixth week - the absence of a hand and foot, microphthalmia, congenital absence of the lower jaw, lens cataract, congenital heart defects (septums and aorta);
• seventh week - congenital heart defects (interventricular septum, pulmonary artery), absence of fingers, cleft palate, micrognathia, epicanthus, round head;
• at the eighth week - congenital heart defects (atrial septal defect), epicanthus, round head, absence of the nasal bone, shortening of the fingers.

As you can see, the causes and the anomalies themselves can be very diverse.

Diagnosis of congenital anomalies.

The main task of diagnosis during pregnancy is to identify chromosomal pathology or fetal malformations. There are many diagnostic medical genetic methods, for the recognition of certain malformations, these are non-invasive diagnostic methods:

• ultrasound research method (which is carried out for all pregnant women not earlier than 3 times during pregnancy: at 10-12 weeks, 20-22 weeks, 30-32 weeks, while ancephaly, undivided fetuses, amelia and many others can be diagnosed),
• determination of various biochemical markers in the mother's blood serum: plasma protein A, human chorionic gonadotropin (during an ectopic pregnancy, the growth rate of this marker will not correspond to the norm, and a change in this hormone may indicate chromosomal disorders), alpha-fetoprotein (an increase in its level increases the risk of developing open malformations of the central nervous system, with a decrease in its level, the risk of developing Down syndrome is possible), estriol (it should increase during pregnancy).

The invasive ones are:

• chorion biopsy (collection of a part of the cells of the fetal egg for research, carried out at 11-12 weeks, a genetic pathology is detected),
• amniocentesis (abstraction of amniotic fluid, hyperplasia of the adrenal cortex is detected in the first trimester of pregnancy, in the second trimester - chromosomal pathology, diseases of the nervous system),
• placentocentesis (examination of placental particles, from 12 to 22 weeks, genetic pathology),
• cordocentesis (blood sampling from the umbilical cord of the fetus for research, blood diseases, infection of the fetus are detected),
• fetal skin biopsy (to diagnose possible skin diseases).

For the diagnosis of anomalies after birth, all known research methods can be used: radiation (radiography, computed tomography, magnetic resonance imaging, radioisotope, ultrasound, angiography and others), endoscopic (bronchoscopy, gastroscopy), various studies of blood, urine and other biological fluids , multiple functional assays and tests, genetic, molecular, immune methods and much, much more. Since for anomalies of various systems and organs, different research methods will be needed.

Indications for termination of pregnancy.

Various violations of the functioning of the organs and systems of the mother can cause an abortion, and this is associated not only with a risk to the health and life of the mother, but also to the unborn child, since these diseases and their treatment can adversely affect him. But the final decision is always made individually. Here are some diseases that can cause abortion: infectious (active tuberculosis, severe forms of viral hepatitis, syphilis, rubella), malignant neoplasms (almost all, they are not only an indication for abortion, but a contraindication to pregnancy in general), endocrine diseases systems (severe thyrotoxicosis, uncompensated hypothyroidism, severe diabetes mellitus), diseases of the blood and hematopoietic organs (aplastic anemia, hemoglobinopathy, leukemia), neurological diseases (multiple sclerosis, myasthenia gravis), eye diseases (diseases of the optic nerve and retina), diseases of the heart - vascular system (deep vein thrombosis, thromboembolism, heart defects), kidney disease (acute glomerulonephritis, urolithiasis), diffuse connective tissue diseases, gynecological diseases, obstetric indications (gestational trophoblastic disease, excessive vomiting of pregnant women, preeclampsia, refractory to treatment, congenital malformations and hereditary diseases that were diagnosed during pregnancy, a high risk of having a child with a congenital, hereditary pathology). But it should be noted that abortion for medical reasons requires the consent of the patient. If any fetal malformations are detected, the pregnant woman herself decides whether to continue the pregnancy or have an abortion.

Prevention of congenital anomalies.

Here the main event should be family planning and pregnancy. Not only the success of the conception itself depends on the quality of this event, but the development of the pregnancy itself, childbirth and the health of the child throughout his future life. It is necessary to pass tests for the presence of sexually transmitted diseases, for the presence of latent infections, to identify all possible chronic diseases, not only in the expectant mother, but also in the father, to undergo genetic testing (to find out what diseases the child may have, to identify various genetic diseases in previous generations ). Naturally, the main factor in the development of a healthy, full-fledged fetus is a healthy lifestyle, not only during pregnancy, but also before it occurs. Refusal of bad habits, good nutrition, exclusion of all harmful factors of a physical, chemical, biological nature. Timely treatment of existing diseases to avoid complications during pregnancy. During the pregnancy itself, undergo the necessary examinations for the timely detection of any deviations in the normal development of the fetus.

Pregnancy is a long-awaited state of a woman. However, this is also a period of worries. After all, the normal course of pregnancy is far from a guarantee that the baby will be born without pathologies. At an early stage, diagnostic measures are necessarily carried out that help to exclude chromosomal pathologies. Anomalies of the fetal chromosomal type are the appearance of an additional (extra) chromosome or a violation in the structure of one of the chromosomes. This happens even during fetal development. So, everyone knows about Down syndrome. This is a disease that develops in utero. It is connected with the appearance of an extra chromosome directly in the 21st pair. Thanks to the diagnosis, as well as external manifestations of the course of pregnancy, such a pathology can be detected even at the early stages of fetal development.

Causes of chromosomal abnormalities

Chromosomal defects can develop for various reasons. Often these are health problems in the mother:

• infections;
• problems with the endocrine system;
• diseases of any internal organs;
• toxicosis during pregnancy;
• previous abortions;
• risk of miscarriage.

An important role is played by ecology, which constantly affects the woman's body, as well as environmental features:

• chemical factors (food, drugs, nicotine, narcotic substances, as well as alcoholic products);
• physical factors (temperature, radiation);
• biological factors in the form of infections and toxins.

An important hereditary factor. Mutations of genes, aberrations of chromosomes are common causes of the development of anomalies. Already when planning pregnancy, you need to think about a balanced diet:

1. All the main ingredients must be present in sufficient quantities on the menu (vitamins, fats, minerals, carbohydrates and proteins).
2. You need to take care of the presence in the menu of products with micronutrients (polyunsaturated fatty acids, trace elements important for the body). Thus, a deficiency of such an element as iodine in the body can lead to a disruption in the development of the brain of an unborn child.

Risk factors

There are many risk factors for developing chromosomal abnormalities. On the part of the mother, these are problems such as:

• Smoking. Leads to fetal growth retardation.
• Age less than 16 years. May lead to preterm pregnancy.
• Age over 35 years. Often leads to developmental delay and chromosomal abnormalities.
• Use of drugs or alcoholic beverages. It is the cause of sudden death syndrome, fetal alcohol syndrome, and withdrawal syndrome.
• Diseases of the thyroid gland.
• Diabetes mellitus often leads to congenital malformations.
• Kidney problems.
• Diseases of the heart and lungs lead to congenital heart defects.
• Anemia.
• Hypertension.
• Polyhydramnios is the cause of the appearance of defects in some internal organs.
• Bleeding.
• infectious diseases.

There are also risks from the fetus:

• developmental delay.
• Multiple pregnancy.
• Anomalies in presentation.

Medications, pregnancy and chromosomal abnormalities

The fetus is affected by many drugs that a woman takes during pregnancy:

• aminoglycosides have a toxic effect on the development of the ear and kidneys;
• aloe helps to increase intestinal motility;
• antihistamines can cause tremors and markedly reduce blood pressure;
• androgens - the cause of the development of fetal defects;
• anticoagulants can cause problems with bone formation, as well as encephalopathy;
• atropine is the cause of brain dysfunction;
• belladonna causes tachycardia in the fetus;
• means to reduce pressure significantly reduce the blood flow to the placenta;
• diazepam can harm the appearance of the unborn child;
• corticosteroids inhibit the functional purpose of the adrenal glands, leading to encephalopathy;
• caffeine damages the fetal liver;
• lithium develops heart defects;
• opiates affect brain activity;
• anticonvulsants significantly delay the intrauterine development of the baby;
• tetracyclines lead to skeletal abnormalities.

signs

The process of development of anomalies in the prenatal state has not been sufficiently studied today. That is why the signs of anomalies are considered conditional. Among them:

• in early pregnancy, pulling pain in the lower abdomen;
• risk of miscarriage;
• non-standard length of the nasal bones;
• low levels of AFP and PAPP-A, as well as elevated levels of hCG. To see these indicators, at 12 weeks a pregnant woman is prescribed an analysis - blood from a vein;
• fetal inactivity;
• slow development of tubular bones;
• neck crease larger than normal;
• renal pelvis are enlarged;
• hypoxia;
• polyhydramnios;
• oligohydramnios;
• dopplerometry and CTG with poor performance;
• large bladder;
• hydronephrosis;
• the presence of cysts in the brain;
• hyperechoic intestine;
• facial deformities;
• cysts in the umbilical cord;
• swelling of the neck and back.

All these signs can also be the norm for the development of the fetus, subject to a similar feature of the body of the child or mother. Blood tests, invasive techniques and ultrasound will help to make sure that chromosomal abnormalities are present as accurately as possible.

Diagnostics

The main task of diagnostic measures that are prescribed during pregnancy is to identify fetal malformations. Today, there are a huge number of methods that allow you to accurately diagnose or exclude the presence of anomalies. Non-invasive methods:

• Ultrasound is prescribed for the entire pregnancy 3 times (up to 12 weeks, at 20-22 weeks and 30-32 weeks).
• Determination of biochemical markers in blood serum. HCG, protein A - deviations from the norm may indicate an ectopic pregnancy or the development of chromosomal disorders. Alpha-fetoprotein - a low level indicates the presence of a risk of developing Down syndrome, and an elevated level will tell about a possible defect in the central nervous system. Estriol - normally should gradually increase with increasing gestational age.

Invasive techniques:

• Chorionic biopsy to identify a genetic abnormality. In this case, a small part of the cells of the fetal egg is taken for analysis.
• Placentocentesis - examination of the placenta. It is carried out at 12-22 weeks of pregnancy with suspicion of genetic pathologies.
• Amniocentesis - analysis of amniotic fluid is performed in the first trimester of pregnancy. It reveals chromosomal pathologies and problems of the nervous system.
• Cordocentesis - a study of blood from the umbilical cord to determine blood diseases and the presence of infections in the fetus.
• Skin biopsy to diagnose skin problems.

Already after the birth of a child, any methods from the arsenal of modern medicine can be used to determine anomalies:

• radiation methods (CT, CTG, X-ray, ultrasound);
• endoscopic;
• research of biological materials;
• functional tests.

Possible pathologies

The development of many anomalies is observed in specific periods of pregnancy:

• 3 weeks - ectopia of the heart, absence of limbs, as well as fusion of the feet;
• 4 weeks - no feet, hemivertebra;
• 5 weeks - splitting of the bones of the face, as well as such terrible problems as the absence of hands, feet;
• 6 weeks - complete absence of the lower jaw, as well as heart disease, lens cataract;
• 7 weeks - the absolute absence of fingers, the development of a round head, an irreparable splitting of the palate from above, as well as epicanthus;
• 8 weeks - absence of nasal bone, shortening of fingers.

The consequences of the development of chromosomal problems are very diverse. It can be not only external deformities, but also lesions, disorders of the central nervous system. The resulting pathologies depend on what kind of chromosome anomaly occurred:

1. If the quantitative characteristics of chromosomes are violated, Down syndrome may occur (in 21 pairs there is one extra chromosome), Patau syndrome (a severe pathology with numerous defects), Edwards syndrome (often occurs in children of elderly mothers).
2. Violation of the number of sex chromosomes. Then the development of Shereshevsky-Turner syndrome is likely (development of the sex glands according to the wrong type), polysomy is characterized by various problems, Klinefelter's syndrome (violations in boys on the X chromosome).
3. Polyploidy usually ends in death in the womb.

Gene mutations are not yet fully understood by scientists. The reasons for their development are still being investigated by experts. But already in 5% of all pregnant women in the world, genetic abnormalities of the fetus are detected.

Approximately 1 in 150 children are born with chromosomal abnormality. These abnormalities are caused by errors in the number or structure of chromosomes. Many children with chromosomal problems have mental and/or physical birth defects. Some chromosomal problems eventually lead to miscarriage or stillbirth.

Chromosomes are thread-like structures found in the cells of our body and containing a set of genes. Humans have between 20,000 and 25,000 genes that determine traits such as eye and hair color and are responsible for the growth and development of every part of the body. Each person normally has 46 chromosomes, arranged in 23 chromosome pairs, in which one chromosome is inherited from the mother, and the second from the father.

Causes of chromosomal abnormalities

Chromosomal pathologies are usually the result of an error that occurs during the maturation of the sperm or egg. Why these errors occur is not yet known.

Eggs and sperm cells normally contain 23 chromosomes. When they fuse, they form a fertilized egg with 46 chromosomes. But sometimes during (or before) fertilization, something goes wrong. So, for example, an egg or sperm cell may develop abnormally, as a result of which they may have extra chromosomes, or, conversely, there may not be enough chromosomes.

In this case, cells with the wrong number of chromosomes join a normal egg or sperm cell, as a result of which the resulting embryo has chromosomal abnormalities.

The most common type chromosomal abnormality called trisomy. This means that instead of having two copies of a particular chromosome, a person has three copies. For example, people with Down syndrome have three copies of chromosome 21.

In most cases, an embryo with the wrong number of chromosomes does not survive. In such cases, a woman has a miscarriage, usually in the early stages. This often happens very early in pregnancy, before a woman can even realize she is pregnant. More than 50% of miscarriages in the first trimester are caused by chromosomal abnormalities in the embryo.

Other errors may occur before fertilization. They can lead to a change in the structure of one or more chromosomes. People with structural chromosomal abnormalities usually have a normal number of chromosomes. However, small pieces of a chromosome (or an entire chromosome) may be deleted, copied, flipped, misplaced, or exchanged with part of another chromosome. These structural rearrangements may not have any effect on a person if he has all the chromosomes, but they are simply rearranged. In other cases, such rearrangements can lead to pregnancy loss or birth defects.

Errors in cell division can occur shortly after fertilization. This can lead to mosaicism, a condition in which a person has cells with different genetic sets. For example, people with a form of mosaicism, Turner syndrome, lack an X chromosome in some, but not all, cells.

Diagnosis of chromosomal abnormalities

Chromosomal abnormalities can be diagnosed before the baby is born by prenatal tests such as amniocentesis or chorion biopsy, or after birth by a blood test.

The cells resulting from these tests are grown in a laboratory and then their chromosomes are examined under a microscope. The laboratory makes an image (karyotype) of all human chromosomes, arranged in order from largest to smallest. A karyotype shows the number, size, and shape of chromosomes and helps doctors identify any abnormalities.

The first prenatal screening consists of taking maternal blood for analysis in the first trimester of pregnancy (between 10 and 13 weeks of pregnancy), as well as a special ultrasound examination of the back of the baby's neck (the so-called collar space).

The second prenatal screening is carried out in the second trimester of pregnancy and consists of a maternal blood test between 16 and 18 weeks. This screening allows you to identify pregnancies that are at higher risk for the presence of genetic disorders.

However, screening tests cannot accurately diagnose Down syndrome or other chromosomal abnormalities. Doctors suggest that women who have abnormal screening test results undergo additional tests, such as chorionic biopsy and amniocentesis, to definitively diagnose or rule out these disorders.

The most common chromosomal abnormalities

The first 22 pairs of chromosomes are called autosomes or somatic (non-sex) chromosomes. The most common disorders of these chromosomes include:

1. Down syndrome (trisomy 21 chromosomes)- one of the most common chromosomal abnormalities, diagnosed in about 1 in 800 babies. People with Down syndrome have varying degrees of mental development, characteristic facial features, and often congenital anomalies in the development of the heart and other problems.

Modern prospects for the development of children with Down syndrome are much brighter than they were before. Most of them have mild to moderate intellectual disability. With early intervention and special education, many of these children learn to read and write and participate in activities from childhood.

The risk of Down syndrome and other trisomies increases with maternal age. The risk of having a child with Down syndrome is approximately:

• 1 in 1300 if the mother is 25 years old;
• 1 in 1000 if the mother is 30 years old;
• 1 in 400 if the mother is 35 years old;
• 1 out of 100 if the mother is 40 years old;
• 1 in 35 if the mother is 45 years old.

2. Trisomy 13 and 18 chromosomes These trisomies are usually more severe than Down's syndrome, but fortunately are quite rare. Approximately 1 in 16,000 babies are born with trisomy 13 (Patau syndrome), and 1 in 5,000 babies are born with trisomy 18 (Edwards syndrome). Children with trisomies 13 and 18 tend to have severe mental retardation and many birth defects. Most of these children die before the age of one.

The last, 23rd, pair of chromosomes are the sex chromosomes, called X chromosomes and Y chromosomes. As a rule, women have two X chromosomes, while men have one X chromosome and one Y chromosome. Sex chromosome abnormalities can cause infertility, growth disorders, and learning and behavioral problems.

The most common sex chromosome abnormalities include:

1. Turner syndrome- This disorder affects approximately 1 in 2500 female fetuses. A girl with Turner syndrome has one normal X chromosome and is completely or partially missing a second X chromosome. As a rule, such girls are infertile and do not undergo the changes of normal puberty unless they take synthetic sex hormones.

Girls affected by Turner syndrome are very short, although treatment with growth hormone may help increase height. In addition, they have a whole range of health problems, especially with the heart and kidneys. Most girls with Turner syndrome have normal intelligence, although they experience some learning difficulties, especially in mathematics and spatial reasoning.

2. Trisomy X chromosome Approximately 1 in 1000 women have an extra X chromosome. These women are very tall. They generally have no physical birth defects, have normal puberty, and are fertile. Such women have a normal intellect, but there may be serious problems with their studies.

Since such girls are healthy and have a normal appearance, their parents often do not know that their daughter has chromosomal abnormalities. Some parents find out that their child has a similar deviation if the mother had one of the invasive methods of prenatal diagnosis (amniocentesis or choriocentesis) during pregnancy.

3. Klinefelter syndrome- This disorder affects approximately 1 in 500 to 1000 boys. Boys with Klinefelter syndrome have two (or sometimes more) X chromosomes along with one normal Y chromosome. These boys usually have normal intelligence, although many have learning problems. When such boys grow up, they have a reduced secretion of testosterone and are infertile.

4. Y chromosome disomy (XYY)- Approximately 1 in 1,000 males is born with one or more extra Y chromosomes. These men have normal puberty and are not infertile. Most of them have normal intelligence, although there may be some learning, behavioral, and speech and language problems. As with trisomy X in women, many men and their parents do not know they have the anomaly until prenatal diagnosis is made.

Less common chromosomal abnormalities

New methods for analyzing chromosomes make it possible to identify tiny chromosomal pathologies that cannot be seen even under a powerful microscope. As a result, more and more parents are learning that their child has a genetic anomaly.

Some of these unusual and rare anomalies include:

• Deletion - the absence of a small section of the chromosome;
• Microdeletion - the absence of a very small number of chromosomes, perhaps only one gene is missing;
• Translocation - part of one chromosome joins another chromosome;
• Inversion - part of the chromosome is omitted, and the order of the genes is reversed;
• Duplication (duplication) - part of the chromosome is duplicated, which leads to the formation of additional genetic material;
• Ring chromosome - when genetic material is removed at both ends of the chromosome, and the new ends unite and form a ring.

Some chromosomal pathologies are so rare that only one or a few cases are known to science. Some anomalies (for example, some translocations and inversions) may not affect a person's health in any way if non-genetic material is missing.

Some unusual disorders can be caused by small chromosomal deletions. Examples are:

• crying cat syndrome(deletion on chromosome 5) - sick children in infancy are distinguished by a cry in high tones, as if a cat is screaming. They have significant problems in physical and intellectual development. With such a disease, about 1 out of 20 - 50 thousand babies is born;
• Prader-Will syndromeAnd(deletion on chromosome 15) - sick children have mental and learning disabilities, short stature and behavioral problems. Most of these children develop extreme obesity. With such a disease, about 1 out of 10 - 25 thousand babies is born;
• DiGeorge Syndrome(deletion on chromosome 22 or deletion 22q11) - about 1 in 4,000 babies are born with a deletion in some part of chromosome 22. This deletion causes a variety of problems that may include heart defects, cleft lip/palate (cleft palate and cleft lip), immune system disorders, abnormal facial features, and learning problems;
• Wolff-Hirshhorn Syndrome(deletion of chromosome 4) - this disorder is characterized by mental retardation, heart defects, poor muscle tone, seizures and other problems. This disorder affects about 1 in 50,000 babies.

With the exception of people with DiGeorge syndrome, people with the above syndromes are infertile. As for people with DiGeorge syndrome, this pathology is inherited by 50% with each pregnancy.

New techniques for analyzing chromosomes can sometimes pinpoint where genetic material is missing, or where an extra gene is present. If the doctor knows exactly where the culprit is chromosomal abnormality, he can assess the full extent of its influence on the child and give an approximate forecast of the development of this child in the future. Often this helps parents make a decision to continue the pregnancy and prepare in advance for the birth of a slightly different baby. TAKE THE TEST (15 questions):

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