Prenatal diagnosis of chromosomal abnormalities. The importance of genetic tests in the prenatal period Interpretation of genetic analysis

Genetics is based on the experience of past years, knowledge of the present and confidence in the future. The once controversial science, whose representatives had more questions than answers, has now received absolute recognition from the entire world community. The unique theoretical and practical basis on the issue of heredity, developed over the past decades, is today available to everyone in the form of a real service. Genetics is of particular importance in the field of family planning.

Genetic tests when planning pregnancy are not a luxury, but rational forethought. If there is a real opportunity to determine the genetic propensity of an embryo (fetus) to a particular disease, only the lazy will not take advantage of this. Unfortunately, many expectant parents do not think about the need to conduct such tests and remember genetics when “pitfalls” are discovered during pregnancy. Why a genetic blood test is needed during pregnancy will be discussed in the article.

A gene is a unit of hereditary structure that encodes information about a person’s individual characteristics: his character, facial features, iris color, etc. Each of us is the owner of certain genes contained in a set of 46 chromosomes. When conception occurs, the maternal and paternal sets of chromosomes are combined - this is the “inheritance” that the unborn child receives from his parents. When chromosomes are damaged, a “breakage” occurs in the genetic structure, which results in one or another pathology. This, of course, cannot but affect the quality of the baby’s physical and mental development. In order to detect and prevent such pathologies in time while expecting a child, the expectant mother donates blood for a genetic test.

Why is genetic analysis needed?

Research based on genetic analysis methods has the following goals:

1. Carry out a genetic compatibility analysis - this way you can establish the fact of paternity, maternity or consanguinity between people.
2. Confirm or refute the patient’s hereditary predisposition to various serious diseases.
3. Calculate DNA traces of infectious pathogens that caused the development of a particular disease.
4. Create a genetic personality passport.

Determining genetic compatibility is better known as a DNA test or paternity test. For this procedure, no special indications are needed; only the wishes of the child’s parents are sufficient. DNA testing most often becomes relevant in the process of divorce or division of property. By the way, it is possible to identify a child’s relationship even during his intrauterine life, during pregnancy.

The undeniable advantage of genetic analysis for various diseases is its reliability. The procedure guarantees 100% results. With its help, you can determine the baby’s predisposition to a number of potential diseases, including:

1. Arterial hypertension.
2. Myocardial infarction.
3. Thrombosis.
4. Diabetes.
5. Dystrophy of bone tissue.
6. Various severe pathologies of the stomach and intestines.
7. Pathologies of the bronchopulmonary apparatus.
8. Thyroid diseases.

If you do not miss the moment and carry out genetic analysis during pregnancy at the right time, you can detect certain abnormalities in the fetus. In some situations, having sufficient information about a disorder in the development of the baby, this problem can actually be corrected and a successful pregnancy can be ensured. Not all pathogens of severe infectious diseases can be detected using traditional diagnostic methods. Then genetic analysis comes to the rescue, and doctors have a real opportunity to quickly identify the DNA of infectious microorganisms in the body of a sick person and obtain maximum information about them in order to choose the right method of treatment. Severe pathologies, such as Down syndrome and Edwards syndrome, are also detected in the early stages of pregnancy through genetic analysis.

Based on the conclusions of specialists, a genetic personality passport is created, which contains a detailed picture of a combined analysis of human DNA. This document is of paramount importance for the patient, as it can be useful throughout life if any health problems arise.

Who is indicated for genetic analysis?

It is not necessary to donate blood for testing in a genetic laboratory, but in most cases, chromosome analysis guarantees peace of mind for the expectant mother throughout her pregnancy. It is mandatory for women who have reason to fear that their child may be born with certain hereditary abnormalities to undergo this procedure. Let's see what could be causing this:

• in the family of one or two parents, there have been cases in the past of the birth of children with mutations, developmental delays or congenital pathologies;
• the expectant mother is over 35 years old, and the father is over 50. Late pregnancy is always associated with the risk of developing severe gene mutations;
• in the past, the pregnant woman was dependent on bad habits such as drinking alcohol, drugs, or had to take medications for a long time;
• being pregnant, the woman fell ill with an infectious disease;
• in the past, the pregnant woman had the sad experience of spontaneous miscarriages or stillbirths.

Genetic tests after a frozen pregnancy

Unfortunately, we are not able to predict and prevent all the misfortunes that life has in store for us. A woman who has suffered a frozen pregnancy understands this especially acutely. How can geneticists help in this case?

A frozen pregnancy is said to occur when the development of the embryo suddenly stops in the early stages of gestation (usually up to 12–13 weeks of pregnancy). This turn of events most often occurs in pregnant women over 40 years of age, but not a single girl/woman of childbearing age is immune from this pathology.

In most cases, frozen pregnancy is explained by genetic abnormalities of the fetus, although this is not the only cause of the pathology. Sometimes representatives of diseases of an infectious nature are to blame for the death of the fetus: herpes, chlamydia, toxoplasmosis. And yet, almost 70% of cases of freezing before the 8th week of pregnancy are associated precisely with chromosomal abnormalities in the fetus. The main feature of genetic abnormalities is their early manifestation, and many of them make the baby’s condition incompatible with life. Such genetic “catastrophes” can occur due to unsuccessful combination of parental genes, but sometimes chromosomes with genetic damage are passed on to the child by the parents themselves. There is an opinion that if a frozen pregnancy occurs not for the first time in a woman, then its cause is most likely a factor of a genetic nature. However, scientists cannot confirm this 100%.

After misfortune, most couples do not give up - they decide to try their luck again. In order to protect a woman from repeating an unsuccessful pregnancy scenario, doctors prescribe her a series of tests, with the help of which the causes of a previous undeveloped pregnancy should be established. Among them, a chromosomal blood test is required. It must be done without fail, especially if the woman has already celebrated her 35th birthday, her medical history contains a note about hereditary diseases in the family, or a frozen pregnancy was not the first in her biography.

Of course, young healthy couples really want to believe that the misfortune happened due to an unfortunate coincidence, and was not at all predetermined by chromosomal “games,” but it is better to verify this with the help of genetic analysis. Only with detailed information about the health status of the future parents will the doctor be able to help them.

Methods for conducting genetic research

There are non-invasive and invasive genetic testing.

Non-invasive research method

Research of this nature is considered the first step in genetic "investigation." It consists of the following procedures:

• biochemical blood test;

A chromosomal blood test of a pregnant patient is carried out, focusing on changes in the concentration of certain proteins in the blood of a pregnant woman with the appearance of an embryo in her body. Certain coefficients of these substances are indicative of various disorders (this includes Down syndrome). When pregnancy proceeds satisfactorily, the concentration of proteins in its body changes naturally, therefore, during genetic analysis, the “age” of the fetus must be taken into account.

During the ultrasound procedure, the size of the space in the child’s collar zone, which is filled with fluid, is measured. This value is directly related to the risk of developing Down syndrome. Excessive fluid volume (in other words, edema) indicates possible pathologies and deviations in the baby’s development.

The first ultrasound is performed at 10–14 weeks of pregnancy. Already at this stage, the doctor can diagnose intrauterine development disorders, if any. The results of chromosomal analysis and possible risks to the fetus are assessed based on all the parameters studied: the volume of fluid in the collar area, data from an analysis of the level of proteins in the blood of the expectant mother, as well as her age.

The earlier genetic tests were carried out, the sooner pathological changes in the child’s body caused by a breakdown of the chromosome set can be detected. If during a genetic study it turns out that the child has a predisposition to one or another genetic disorder, the examination of the pregnant woman will certainly continue. They do this using invasive methods.

Invasive research methods

Using invasive methods, it is possible to detect about 400 types of abnormalities in the fetus with a high probability. Invasive research methods are considered:

• amniocentnesis. The material for this procedure, which is carried out at 15–18 weeks of pregnancy, is amniotic fluid. Amniotic fluid is collected by piercing the uterus with a long needle;
• Chorionic villus biopsy. During the procedure, the cells that are the material for creating the placenta are studied. The material is collected by piercing the abdominal cavity or through the cervix. However, the method has one significant drawback - it increases the risk of spontaneous miscarriage;
• placentocentnesis. The method is relevant after an infectious disease suffered by the expectant mother. In this case, the cells that make up the tissue of the placenta are examined. The procedure is prescribed in the second trimester of pregnancy and is performed under general anesthesia: a small piece of the placenta is taken for analysis through a puncture of the anterior abdominal wall;
• cordocentnesis. This test requires umbilical cord blood. To collect biological material, a thin long needle is inserted into the umbilical cord. The method is associated with some risks: attempts to take blood are not always successful, and there is a risk of miscarriage.

Normal and abnormalities of genetic analysis during pregnancy

There are borderline indicators for chromosomal analysis in pregnant women, with the help of which the doctor judges how healthy the baby is and whether he is developing correctly:

1. High risk – 1:200. The expectant mother is sent for additional diagnostic examination. The material for analysis is the villous chorion or amniotic fluid.
2. The average degree of danger is from 1:201 to 1:3000. In this state of affairs, the patient is prescribed additional screening in the period from 16 to 18 weeks of gestation. This study can confirm or refute a probable threat to fetal development.
3. Low risk – less than 1:3001. This indicator suggests that the expectant mother has nothing to worry about: her baby is not threatened with any genetic abnormalities.

Genetic analysis during pregnancy. Video

The birth of a child is a joyful event for parents and family members. But pregnancy does not always proceed well and without complications. Recently, more and more genetic diseases have been observed. This is influenced by numerous factors.

You can prevent your child from getting sick

Heredity plays a huge role in the formation of a person. We all borrowed certain appearance, character and health features from our parents and grandparents from different generations.

Genetics is a science that studies the mechanisms of diseases transmitted by inheritance. Currently, pregnant women are recommended to undergo examination by a geneticist in order to exclude pathologies or to detect them in a timely manner. How does this procedure happen and is it so important?

The importance of genetic counseling during pregnancy

This procedure gained popularity in the last century because science has advanced far and it has become possible to diagnose diseases that are inherited or arise due to a number of other reasons in utero. Every parent is concerned about the health of their unborn baby, so the examination is important, especially for couples where the risk of pathologies is high. For example, if one of the partners suffers from epilepsy, hemophilia, asthma, diabetes and other serious illnesses.

When planning a pregnancy, many couples come for a consultation with a geneticist in advance to rule out problems, but it is not too late to do the procedure even after conception has taken place.

Consultation with a geneticist is necessary to ensure the baby’s health, identify predisposition to certain diseases, or identify existing mutations and pathologies.

This procedure is freely available and parents can make an appointment and undergo examination at any time. During the conversation, be sure to talk about the reasons, possible suspicions and take the appropriate tests.

Women at risk

As in any other case, there is a risk group that includes women in labor:

1. Over the age of 35. Patients have a high risk of having a child with disabilities.
2. If you have relatives who suffer from hereditary diseases.
3. With a history of several miscarriages, stillbirths, and infertility.
4. If the couple is blood relatives.
5. Contact of a woman with aggressive toxic substances, radiation exposure or chemical exposure.
6. The presence of children with chromosomal pathologies.
7. Women with diseases of the endocrine system.
8. Multiple pregnancy.

Additional reasons for conducting

Additional factors for prescribing the procedure are negative tests, perinatal screening indicators, or the pregnant woman’s own desire. Previous illnesses during pregnancy and taking medications that can adversely affect the health of the fetus.

What does a geneticist do during pregnancy?

The procedure is carried out using two methods:

1. Non-invasive - the woman undergoes an ultrasound and takes a biochemical blood test for markers.
2. Invasive - involves penetration into the uterine cavity, from where materials for examination are taken to identify the karyotype of the fetus. Chorionic villus biopsy, amniocentesis, placentocentesis, and cordocentesis are used. Cells are collected from the placenta, umbilical cord, amniotic fluid and fetal blood. These procedures are allowed only under strict doctor’s orders and in a hospital setting; after the manipulations are completed, the woman needs some time to get in order.

There are three levels of threat to a child:

1. Probability 10% - this indicator means that there is no danger to the baby’s health.
2. A value from 10% to 20% – the probability of having a healthy child and one with diseases is the same. This result requires further examination to identify the exact risk.
3. Above 20% – there is no possibility of conceiving a baby without pathologies; an IVF procedure is recommended for bearing a healthy child.

Particular attention is paid to women with complex and multiple pregnancies. For example, patients with diabetes must undergo testing for blood glucose (glucose tolerance test), protein and liver enzymes.

There is no need to ignore the genetic research procedure even if there is no reason for anxiety or discomfort while carrying a child.

The main danger of chromosomal abnormalities is that in most cases they are completely silent and have no symptoms. A genetic disease can appear even after several generations, so it is important to get advice and tests to make sure that the baby does not have any problems.

Despite the high level of medicine, there is a percentage of error. There are cases when specialists identified mutations with which the child is not viable, but the woman had a healthy baby. However, such an outcome has a low probability.

How long does it take to consult a geneticist during pregnancy?

The first examination is usually scheduled at the end of the first trimester - 10-12 weeks. If the results are excellent and do not require additional tests, then the next consultation takes place after 20 weeks.

Then a control study is done during the 30-32 weeks of pregnancy. In case of a difficult pregnancy and possible threats, a genetic appointment can be carried out at other times.

After the birth of a child, blood is taken from the toes of the newborn for the presence of pathologies.

Genetic testing is 85% likely to detect problems.

The current ecology and rhythm of people's lives do not have a very favorable effect on health. Therefore, in order to conceive and give birth to a healthy child without pathologies, it is strongly recommended by experts to visit a geneticist before planning.

Useful video

A genetic blood test is a type of laboratory test that allows you to evaluate a person’s chromosomes to identify pathological conditions. This study is also used to establish the degree of relationship or for prevention.

Depending on the purpose of the study, the following types of genetic analysis are distinguished:

• DNA analysis;
• karyotyping.

DNA analysis

A DNA (deoxyribonucleic acid) blood test is a test that allows you to identify a person by studying a unique nucleotide sequence. This “genetic trace” is individual for each person (with the exception of identical twins) and does not change throughout life.

Molecular genetic blood tests can determine:

1. Possible diseases. DNA testing of biological material allows for timely detection of hereditary diseases. If there are cases of mental disorder or oncology in the family, this test determines the predisposition to the development of a similar problem in descendants.
2. Individual intolerance to medications. In cases where there is suspicion of hypersensitivity to a certain group of drugs, DNA analysis may be indicated.
3. Relation degree. One of the most common reasons for conducting research is the need to establish family ties between people.
4. Factors of infertility. In reproductive centers, couples who have difficulty conceiving are required to undergo a DNA test.
5. Tendency to develop alcoholism or drug addiction. Such a predisposition can be established by identifying the genes responsible for the synthesis of enzymes for the breakdown of alcohol molecules and other compounds.

Karyotyping

Karyotyping refers to a technique of cytogenetic analysis, thanks to which it is possible to study the chromosome set of a person. A similar examination is carried out among married couples wishing to have a child.

Karyotype is the chromosome set of each person, containing a complete description of the characteristics of all its components, including:

• quantity;
• shape;
• size, etc.

The human genome contains 46 chromosomes, which, in turn, are divided into 23 pairs.

Autosomal (first 44) - designed to transmit hereditary characteristics:
(hair color, eye color, anatomical features).

The last chromosome pair is the sex chromosomes, with the help of which it is possible to determine the karyotype:

• women (23XX);
• men (23XY).

The main objectives of karyotyping are:

1. Determination of discrepancies in the chromosome set of spouses. The analysis is carried out to prevent the birth of children with developmental defects or other genetic pathologies.
2. Identification of the number and affiliation of chromosomes, characteristics of their structure.
3. Establishing the causes of infertility, manifested in changes in the multiplicity of chromosomes.

When can a genetic blood test be prescribed?

Among the mandatory medical indications for conducting the study are the following:

• living in an environmentally unfavorable area;
• infertility for which the cause has not been established;
• age from 35 years (carried out even among couples where at least one spouse is over 35 years old);
• unsuccessful multiple attempts at artificial insemination;
• pathologies in the development of spermatogenesis without an established cause;
• hormonal disorders in women;
• presence of genetic diseases in the family;
• constant contact with chemicals;
• marriages between close relatives;
• recorded cases of spontaneous abortion, including premature birth and stillbirth.

Analysis during pregnancy

A timely DNA test shows the baby’s developmental defects even before birth and will help create a genetic map of the child. Most often, in this case, a “genetic pairing” study is prescribed.

Invasive

To carry out the analysis, it is necessary to collect biological material not only from the mother, but also from the fetus. In this case, during the research, penetration occurs through the woman’s abdominal cavity. The invasive diagnostic method makes it possible to finally confirm the preliminary diagnosis, but carries a certain threat to the baby.

Features of the analysis:

1. The test can be carried out already in the first trimester of pregnancy; venous blood is taken for testing.
2. Genetic pair analysis involves the study of specific protein structures (beta-hCG and PPAP-A), which are considered the main indicators of the presence of genetic pathologies.
3. It is prescribed in combination with an ultrasound of the uterus and analysis of the karyotype of the parents. To study the karyotype, blood is taken from the baby's umbilical cord.
4. In conclusion, the doctor assesses the degree and risks of developing hereditary pathologies in the child, prescribes treatment and records the data in the genetic map.

Non-invasive

Non-invasive diagnostic techniques have emerged in response to the possible complications and risks of invasive genetic testing. The most popular such method is Tranquility NIPT.

Analysis Features:

1. To obtain a DNA result, it is necessary to examine the mother's blood. Starting from the first month of pregnancy, the circulation of fetal cells is activated in the mother’s body. Towards the end of the first trimester, their concentration reaches a limit, which is sufficient to be determined in genetic analysis.
2. The study has a high level of reliability. The accuracy of diagnosing Down syndrome is more than 99.9%.
3. The test does not pose a risk to the development of the fetus or the health of the mother.
4. The study is carried out at 10-12 weeks of pregnancy.
5. The results are prepared within 15 working days.

Genetic analysis of newborns

With timely diagnosis of pathologies and properly selected treatment, many problems can be solved from birth.

Features of the study:

1. Blood is taken to test for genetic diseases. For full-term babies, sampling takes place on the 4th day after birth, and for premature babies - on the 7th day.
2. If a child is suspected of having a genetic pathology, the doctor will prescribe further examination. The type of diagnosis depends on the nature of the disease.
3. Genetic analysis of newborns makes it possible to timely determine the presence of pathologies such as cystic fibrosis, adrenogenital syndrome, phenylketonuria and others.
4. To obtain additional information or diagnose other diseases, a DNA test is prescribed. Venous blood is used as biological material.

"Paternity Test"

Establishing kinship is used not only in the medical field, but is also often necessary to resolve legal disputes. Since parents pass on their genetic material to the child, this analysis reveals matching areas in relatives. A high percentage of matches means a high probability of proving a relationship.

Unlike other genetic tests, biological material for paternity testing can be taken from different parts of the body. The most commonly used scraping is the inside of the cheek. Paternity testing is a lengthy process. But in this case, it is better to trust the specialists and wait until the results are compared many times.

The accuracy of establishing kinship with this method is more than 99%.

Instructions for collecting material to perform a genetic test to establish paternity at home. The video was taken from Evgeniy Ivanov’s channel.

Genetic analysis as a key method of predictive medicine

The study of genetic material allows us to identify possible diseases in the future. This is due to the fact that not all genotype failures result in one or another pathology. In most cases, environmental factors also play an important role. . If you do a DNA test in a timely manner, you can avoid the development of many incurable diseases.

Such pathologies include:

• atherosclerosis;
• diabetes;
• bronchial asthma;
• hypertonic disease;
• oncology.

Thanks to the development of medicine, several methods are now available to study genetic information. Each option is selected depending on the possibilities and the case.

Basic techniques:

1. Microchip technology. In the diagnostic process, a DNA chip is used, created by analogy with an electronic chip to isolate multiple DNA strands. Modern microchips are capable of identifying millions of different mutations and measuring gene expression. The chip itself is made of glass or silicone, onto which DNA is applied during a machine printing process.
2. Comparative genomic hybridization. The technology involves analyzing changes in the number of copies of relative ploidy levels in the material under study in relation to the control sample, which is the reference.
3. FISH technology. The principle of operation of the method is based on the phenomenon of hybridization—binding the DNA of the patient sample under study with a DNA probe.
4. Polymerase chain reaction. The technique involves a rapid increase in the concentration of isolated DNA sections in human biological material to determine a particular pathology.

The predictive function of genetic analysis is to predict the development of possible pathologies.

Are there any contraindications and restrictions?

In order to do a genetic analysis, doctors do not identify significant contraindications and restrictions. The procedure can be performed by people of any age and pregnant women. The only note, when it comes to expectant mothers, is that an invasive genetic test is recommended after 18 weeks.

Before conducting the study, it is advisable to exclude the following:

• smoking;
• consumption of alcoholic beverages;
• kisses;
• chewing gum use.

How is it carried out?

The main biological material for research is blood. Most often, venous blood is needed.

Order of conduct:

1. Before the procedure, the patient must fill out a questionnaire. It is important to provide accurate data as this can significantly affect the outcome of the analysis.
2. Next, the patient is taken to the office where the material is collected. It is better to take a blood test on an empty stomach, preferably in the morning.
3. The resulting biological material is placed in a test tube and sent for testing to the laboratory.

Decoding the results of genetic research

The interpretation of the results obtained for genetic diseases should be carried out exclusively by a geneticist. Only an experienced specialist can correctly draw a conclusion based on the data obtained. The preparation process and the decoding itself last from several weeks to a month.

How much does a DNA test cost?

Price for genetic research services at ON Clinic:

Name	Price, rub
Genetic risk of coagulation disorders	5000
Genetic risk of hyperhomocysteinemia	2500
Immunological compatibility of partners (HLA typing)	4500
Andrenogenital syndrome	7500
Polycystic ovary syndrome	3500
Polymorphism of genes encoding metabolic enzymes	4500
Genetic factors of male infertility	4000
Risk of developing osteoporosis	9000
Genetic lactose intolerance	1500
Pharmacogenetics: sensitivity to warfarin	3500
Breast Cancer Predisposition (BRCA)	4000
Risks of developing arterial hypertension	3500
Susceptibility to interferon and ribaverin in patients with viral hepatitis C	2500
Determining the sex of the fetus (from the 9th week of pregnancy)	3500
Determination of the Rh factor of the fetus (from the 11th week of pregnancy)	3000
Predisposition to celiac disease	3000
Cystic fibrosis	3000

Prices for services at the Treatment and Diagnostic Center "Kutuzovsky":

Name	Price, rub
Study of the reproductive factor AZF (loci A, B, C)	7370
Genetic risk of coagulation system disorders (F2, F5, F7, FGB, F13A1, SERPINE1, ITGA2, ITGB3 - 8 points)	5630
Genetic defects of folate cycle enzymes (MTHFR, MTR, MTRR - 4 points)	3760
Genetic predisposition to hypertension (AGT, ADD1, ACE, AGTR1, AGTR2, CYP11B2, GNB3, NOS3 - 10 points)	10390
Genetic risk of pregnancy complications and fetal pathology (F2, F5, F7, FGB, F13A1, SERPINE1, ITGA2, ITGB3, MTHFR, MTR, MTRR - 12 points)	8455
Genetic predisposition to osteoporosis (blood)	6590
Genetic test for lactose intolerance: MCM6: -13910 T>C	1880
Diagnosis of Gilbert's syndrome (UGT1 gene mutation)	3930
Congenital dysfunction of the adrenal cortex (CYP21OHB gene mutation - 10 indicators)	9550
Genetic factors in the development of polycystic ovary syndrome, (blood)	3300
Determination of SNP in the human IL28B gene	2560
Karyotype research (karyotyping)	9220
Genetically determined sensitivity to warfarin (VKORC1, CYP2C9, CYP4F2 - 4 points)	3760
Blood coagulation system. Study of polymorphisms in genes: F5 (Leiden mutation, Arg506Gln) and F2 (prothrombin 20210 G> A)	2310
Warfarin. Determination of therapeutic dose. Study of polymorphisms in genes: VKORC1-1639/3673, CYP4F2 V433M, GGCX rs11676382, CYP2C9*2, CYP2C9*3, CYP2C9*5, CYP2C9*6	4000
Cytogenetic study of bone marrow cells (FISH method)	14030
Prices are relevant for three regions: Moscow, Chelyabinsk, Krasnodar.

Photo gallery

results Genetic test

Video

A video filmed by the Miracle of Technology channel explains whether it is worth doing a genetic test and DNA decoding.

Immediately after a positive pregnancy test, a woman begins a new life, because from that moment the rule “good for me is good for the child” comes into force, which means you need to take care, monitor your health and be under the constant supervision of an obstetrician-gynecologist. A pregnant woman goes to see a doctor every 2 weeks, and in case of a severe pregnancy, every week. And monitoring of her well-being and the child’s development process is carried out not only by examination by a gynecologist, but also by collecting tests.

One of the most important and informative is genetic analysis. In this article we will try to explain why it is needed, what the risks are and how it is deciphered.

What genetic analysis shows: what is it?

Geneticists study genes responsible for the transfer and embodiment of hereditary information in human DNA, that is, they can calculate and say what the result of fertilization of an egg and sperm will be, what characteristics will dominate in a future person and, most importantly, what diseases and abnormalities may appear as a result of such fertilization. Therefore, of course, it is better, if possible, to do such an analysis before pregnancy in order to avoid bad consequences, if possible, undergoing a course of treatment for hidden infections in future parents.

But not everyone knows about this; only a few turn to a geneticist when planning a family - and we have what we have, that is, the need to carry out analysis after the fact, in the presence of a fetus. So, using genetic analysis you can find out the following information:

• Do the parents have genetic compatibility, determine paternity and other consanguinity.
• The likelihood of a child’s genetic predisposition to common diseases.
• What infectious agents are present in the body of mother and child.
• Generate a genetic personality passport, which is a unique form of combined DNA analysis, which contains data about the profile and uniqueness of a person. This data can help a person throughout his life, helping to prevent many health problems.

When and how is genetic analysis done during pregnancy: at what stage?

Genetic research is carried out using two methods: non-invasive and invasive. Non-invasive tests include biochemical blood tests and ultrasound.

The first ultrasound is performed at 10-14 weeks of pregnancy. With its help, you can see the presence of any violations in the development of the child. A biochemical blood test must be taken in the first months. Such studies in the early stages make it possible to determine the presence of pathological changes in the fetal body, the cause of which is heredity, or in other words, a violation of the integrity of the chromosome set. If signs of pathology are detected, the pregnant woman is sent for a repeat ultrasound, which is performed at 20-24 weeks.

With the help of such a study, minor developmental defects can be identified. If, after a biochemical blood test (blood is taken from a vein) and ultrasound, there are still some suspicions about possible fetal pathologies, they resort to invasive methods that help identify about 400 different pathologies. These are amniocentesis, chorionic villus sampling, cordocentesis and placentocentesis.

During amniocentesis at 15-18 weeks, amniotic fluid is taken with a large needle for examination. The procedure is not dangerous for the child. Chorionic villus biopsy examines the cells that actually form the basis of the future placenta. To obtain material for analysis, tissue is taken from the cervix or a puncture is made in the abdominal cavity. Everything is done under anesthesia.

Placentocentesis is usually prescribed in the case of an infectious disease suffered during pregnancy. This is done in the second trimester, when the placenta is already well formed. After the administration of painkillers, the uterus is punctured through the anterior abdominal wall.

After the 18th week of pregnancy, cardiocentesis can be performed - umbilical cord blood testing. Blood is taken by puncture through the uterine cavity. Invasive methods are risky, because any intervention in the amniotic space is fraught with infection; it is carried out only as a last resort and only with the permission of the child’s parents.

Decoding genetic analysis: results, norm

In the first trimester, as a result of an ultrasound and a biochemical blood test for hCG and PAPP-A, the risk of developing Down syndrome and Edwards syndrome in a child is determined. An experienced ultrasound specialist can identify the presence of the disease by the so-called TVP indicator (thickness of the collar space). If the cervical fold of the embryo is thicker than 3 mm, then there is a high risk of having the syndrome. The rhythm of the fetal heartbeat and the visibility of the bladder, which should be noticeable by 12 weeks, are also taken into account.

The second mandatory test in the first trimester is a biochemical blood test for the level of hCG and the free β-subunit of hCG (β-hCG). HCG and free β (beta) subunit of hCG are different indicators, each of which can be used as a screen for Down syndrome and other diseases. But measuring the level of the free beta subunit of hCG can more accurately determine the risk of Down syndrome in an unborn child than measuring total hCG. The norm of total hCG by week of pregnancy (counting is not from the moment of conception, but from the first day of the last menstruation!):

3 weeks: 5-50 honey/ml (mIU/ml)

4 weeks: 5-426 honey/ml (mIU/ml)

5 weeks: 18-7,340 mIU/ml

6 weeks: 1,080-56,500 mIU/ml

7-8 weeks: 7,650-229,000 mIU/ml

9 -12 weeks: 25,700-288,000 mIU/ml

13 – 16 weeks: 13,300-254,000 mIU/ml

17 -24 weeks: 4,060-165,400 mIU/ml (mIU/ml)

25 – 40 weeks: 3,640-117,000 mIU/ml

Of course, the level of the hormone human chorionic gonadotropin may differ slightly from the norm. More important is its change during pregnancy (dynamics).

Norms for the free β-subunit of hCG in the first trimester:

9 weeks: 23.6-193.1 ng/ml, or 0.5-2 MoM

10 weeks: 25.8-181.6 ng/ml, or 0.5-2 MoM

11 weeks: 17.4-130.4 ng/ml, or 0.5-2 MoM

12 weeks: 13.4-128.5 ng/ml, or 0.5-2 MoM

13 weeks: 14.2-114.7 ng/ml, or 0.5-2 MoM

Since the norms in ng/ml may vary from one laboratory to another, the data provided is not conclusive and you should always consult your doctor. If the result is indicated in the MoM, then the standards are the same for all laboratories and for all analyses: from 0.5 to 2 MoM. MoM is a special value that shows how much the obtained analysis result differs from the average result for a given stage of pregnancy.

In most cases, hCG levels double approximately every 1-3 days by week 4, and then approximately every 3.5 days by week 9. After 10-11 weeks of pregnancy, hCG begins to fall - this is normal. If the free β-subunit of hCG is higher than normal for your gestational age, or exceeds 2 MoM, then the baby has an increased risk of Down syndrome. If the free beta subunit of hCG is below normal for your gestational age, or less than 0.5 MoM, then the baby has an increased risk of Edwards syndrome.

PAPP-A, or “pregnancy-associated plasma protein A,” is the second indicator used in first-trimester biochemical screening. Its amount increases during pregnancy, and deviations in the indicator may indicate various diseases in the unborn child.

The norm for PAPP-A depending on the stage of pregnancy:

8-9 weeks: 0.17-1.54 mU/ml, or 0.5 to 2 MoM

9-10 weeks: 0.32-2.42 mU/ml, or 0.5 to 2 MoM

10-11 weeks: 0.46-3.73 mU/ml, or 0.5 to 2 MoM

11-12 weeks: 0.79-4.76 mU/ml, or 0.5 to 2 MoM

12-13 weeks: 1.03-6.01 mU/ml, or 0.5 to 2 MoM

13-14 weeks: 1.47-8.54 mU/ml, or 0.5 to 2 MoM

If PAPP-A is below normal for your gestational age, or less than 0.5 MoM, then the baby has an increased risk of Down syndrome and Edwards syndrome.

If PAPP-A is higher than normal for your gestational age, or exceeds 2 MoM, but other screening indicators are normal, then everything is fine, don’t worry. According to studies, in the group of women with elevated PAPP-A levels during pregnancy, the risk of diseases in the fetus or pregnancy complications is no higher than in other women with normal PAPP-A levels.

To correctly calculate the risk, it is necessary to take all tests in the same laboratory in which the risk is calculated. The risk calculation program is configured for specific parameters, individual for each laboratory. Therefore, for another laboratory you will need to take all the tests again.

The program gives the result as a fraction, for example: 1:10, 1:250, 1:1000, where, for example, a risk of 1:300 means that out of 300 pregnancies with indicators like yours, one child will be born with Down syndrome and 299 healthy children. If the result is positive, you will need to be screened in the second trimester.

Is it necessary to do a genetic test during pregnancy?

Most gynecologists agree that it is necessary to do a genetic analysis if a woman is over 35 years old, there are relatives in the family with hereditary diseases, there are children with developmental disabilities, during pregnancy the woman was subjected to x-rays, took drugs, or suffered from infectious diseases. This is a risk group.

If none of this applies to you, then you have the right to refuse the test.

Is genetic analysis necessary during pregnancy: pros and cons

In no case should an analysis be carried out if the woman is not feeling well, has toxicosis, or has a viral infection, since all this will affect the result and distort it. Also, for many women, screening itself is stressful and not entirely desirable, especially in the early stages. And it is impossible to change the situation with a terrible diagnosis, except by terminating the pregnancy (genetic diseases cannot be treated).

Therefore, the bitter truth will darken the entire period of pregnancy for that mother who does not agree to an abortion. But on the other hand, this knowledge will help parents learn how to raise such a child; they will be ready to provide him with the right conditions and care.

Genetic analysis during pregnancy: price and reviews

The price of this analysis is quite high, since it is done only in private laboratories. Many women complain that all this money and nerves are not worth exhausting themselves so much, because for the correct indicator, the accuracy of determining the gestational age, which is often relative, is important.

If you do not have indications for screening and you are not at risk, then you can save on this and rely only on optimism and confidence in a favorable completion of the pregnancy. And for those for whom money is not important and who want to make sure of the baby’s health, there are a huge number of laboratories at their disposal, the addresses and price lists of which are available on the Internet. Find the one that is closest to you in the city and has a high reputation - and go ahead.

We wish you and your baby good health!

Especially for - Angelika Golyana