Visiting a geneticist when planning a pregnancy. Genetic analysis when planning: why is it needed

06.04.2020

Genetic examination when planning pregnancy plays a very important role, as it makes it possible to minimize the likelihood of having a baby with any pathologies. Unfortunately, most of the embryos die in the early stages precisely because of various anomalies and genetic failures. What is this examination, you will find out below.

For some couples, a genetic consultation in preparation for conception is mandatory:

if any of the parents in the family had genetic diseases,
Husband and wife are related to each other
previous pregnancies ended in stillbirth, miscarriage, missed abortion,
the couple has children with developmental disabilities,
age: women under 16 or over 35 years old, men over 40 years old,
at least one of the parents has been in contact with radiation, chemicals that can adversely affect the conception and development of the baby,
one of the spouses took drugs that are incompatible with pregnancy,
the couple fails to conceive a baby for 12 months or more.

Important: one of the main causes of miscarriage is the genetic incompatibility of husband and wife. This happens if the HLA (this is a human leukocyte antigen) of a man largely coincides with the HLA of a woman. As a result of this combination, the woman's body perceives the embryo as a foreign body, rejecting it.

The main task of a genetic study when planning a pregnancy for the compatibility of spouses is to identify discrepancies in the chromosomes of future parents. And the more inconsistencies, the higher the chance to endure and give birth to a healthy baby.

What is a pregnancy planning consultation?

Even a healthy person can be a carrier of damaged genes.

At the appointment, the geneticist will conduct a thorough survey of the couple about past illnesses, lifestyle, chronic ailments, as well as the health of the husband's and wife's relatives. All this information is needed by a specialist in order to schedule an examination for future parents. As a result of the analyzes, the geneticist individually draws up a genetic prognosis for the development of the child, and also determines the risk of developing diseases and gives recommendations on planning pregnancy.

If a couple is in a risk group, they must undergo cytological examination(in order to determine the quantity and quality of chromosomes), a man must pass (to exclude possible pathologies in the sperm), you also need to pass HLA - typing(to determine the compatibility of spouses).

There are 3 levels of risk, which are determined by the results of a genetic study:

low (up to 10%) - the couple will have a healthy baby,
medium (10-20%) - the possibility of some pathologies of fetal development is not excluded. Therefore, a woman will need to be observed during childbearing,
high - in this case, it is better to refrain from pregnancy, since there is a high probability of having a baby with serious pathologies (but you can use it).

What is the essence of cytogenetic analysis?

Cytogenetic analysis is a blood test of spouses, which makes it possible to:

Analyze the chromosome set of a man and a woman.

Even an absolutely healthy person can be a carrier of some chromosomal rearrangements and not be aware of it. This will not affect his health in any way, but the development of the child may not be displayed in the best way.

Assess the degree of risk for future pregnancies, taking into account past complications (miscarriages, missed pregnancies, birth of children with developmental anomalies).
Assign and explain the need for prenatal diagnosis in future pregnancies.

This type of diagnosis involves conducting tests in the process of bearing a child. It allows you to clarify the condition of the fetus, as well as determine its chromosome set.

Interesting: Chromosomes can only be seen under a microscope at certain stages of cell division. Therefore, in order to study the chromosome set of future parents, they take blood from which lymphocytes are isolated. Next, the cells are stimulated to start dividing and, at a certain stage, they are treated with a special solution that stops division precisely at the stage when the chromosomes are visible.

Then a special dye is used, thanks to which each individual chromosome acquires a specific shape. A geneticist studies chromosomes 11-13 in order to identify changes in the karyotype (set of chromosomes).

Methods of genetic examination

After the woman is registered, the gynecologist conducts a thorough survey and examines the patient's outpatient card in order to have an idea of the possible risks to the development of the fetus.

Sometimes already at such an early date, a pregnant woman is referred for a consultation with a geneticist. The period at which a pregnant woman needs to be seen by genetics depends on the indications:

All methods of genetic examination are divided into 2 groups: invasive and non-invasive.

Non-invasive methods

The first ultrasound examination is carried out for a period of 11-12 weeks. During this period, it is already possible to identify some malformations of the fetus. This may be indicated by a thickening of the collar zone of the fetus (often this is a sign of Down's syndrome).

Women with similar ultrasound results are referred for additional studies that make it possible to obtain a sample of cells from the placenta in order to reliably determine the chromosome set of the fetus.

The second ultrasound - the examination is carried out for a period of 20-22 weeks. During this period, deviations in the development of the face, arms and legs, as well as the internal systems and organs of the fetus, can be detected.

Ultrasound for a period of 30-32 weeks allows you to assess the state of the circulatory system, as well as determine the delay in fetal development.

This is how amniocentesis is performed.

Biochemical blood test (screening)

Embryonic tissues of the fetus produce special proteins: protein (PAPP), human chorionic gonadotropin (hCG), alpha-fetoprotein (AFP). By changes in the concentration of these substances in the blood of a pregnant woman, various pathologies of fetal development can be determined.

Such studies are carried out within a certain period of time. The level of PAPP and hCG is determined for a period of 10-13 weeks. AFP level - for a period of 16-20 weeks. If the results of the study are outside the normal range, the woman is referred to a geneticist.

Invasive diagnostic methods

These studies are carried out exclusively for compelling medical reasons, as they can harm the health of a woman and a child. Invasive diagnostics involves taking material (cord blood, placental cells, amniotic fluid) from the uterus to determine the karyotype of the fetus and exclude or confirm diagnoses with developmental delay.

These studies are carried out in a hospital under ultrasound control. After the tests, the woman is under the supervision of specialists for another 3 hours. Sometimes, certain medications are prescribed to prevent complications in a pregnant woman. Diagnostic methods have been developed to identify 300 out of 5,000 existing hereditary diseases.

TO invasive research includes:

Chorionic biopsy

This is a collection of cells from the placenta. It is carried out for a period of 9-12 weeks. The material is taken through the abdominal wall of the woman. The results are obtained 3-4 days after the study. The risk of miscarriage after a chorionic biopsy is about 2%. This method has the following advantages: early term, quick result, which allows to identify serious pathologies of fetal development and terminate the pregnancy in the early stages.

Amniocentesis

This is the collection of amniotic fluid for a period of 16-24 weeks. This invasive method is the safest, as the risk of miscarriage after amniocentesis is only 1%. But there are some drawbacks: the cells obtained after sampling are not enough for analysis. They need to breed, and for this you need to spend a lot of time - about 2-6 weeks.

Cordocentesis

Cord blood analysis is a highly informative method that takes about 5 days to obtain results. It is carried out for a period of 22-25 weeks.

Placentocentesis

This analysis involves the collection of placental cells for research. It is carried out for a period of 12-22 weeks. The risk of complications after analysis is 3-4%.

All of the above methods of examination are carried out with anesthesia and under strict ultrasound control.

The genotype of father and mother when planning pregnancy

In genetics, there are two main concepts: phenotype and genotype. A genotype is a set of genes. Phenotype - external manifestations of a particular trait, which depends on both the genotype and external factors.

Ultrasound at 9-11 weeks allows you to identify abnormalities in the development of the fetus

A person has about 35 thousand genes that are unique, like fingerprints. The study of the genotype makes it possible to find out the genetic characteristics of a person, his heredity, compatibility with another person, predisposition to many diseases.

People with the same blood type can have a completely different set of genes.

Interestingly, there are some amazing patterns:

if mom and dad have the first blood group, the baby will have only the first group,
if mom or dad has the first group, the child cannot have the fourth blood group,
if at least one of the parents has the fourth blood type, the baby cannot have the second.

Prevention of genetic abnormalities of the fetus

In recent years, when planning pregnancy, periconceptual prophylaxis has been widely practiced, which makes it possible to significantly reduce the likelihood of having a baby with any congenital anomalies. Periconception prophylaxis suggests:

Examination of future parents before conception, which makes it possible to identify and treat various diseases. Infections, hormonal disruptions, disruptions in the endocrine system can adversely affect the conception and formation of organs and systems of the fetus.
Taking multivitamin complexes 2-3 months before the intended conception. Preparations must contain: B vitamins, folic acid, ascorbic acid, vitamin A.
Genetic examination when planning pregnancy allows you to identify various pathologies of fetal development in the early stages.

4. Closely related marriages are highly undesirable: the closer the relationship between husband and wife, the higher the risk of having a child with serious developmental anomalies.

Consulting a geneticist when planning a pregnancy is far from uncommon today. The list of indications is wide. It is necessary for couples in the family who have serious hereditary diseases. Also, the help of geneticists is needed in case of unsuccessful previous pregnancies. Analysis of the hereditary material of a married couple will determine the likelihood of having healthy children.

Read in this article

Do I need to consult a geneticist when planning

A visit to a doctor of this specialty is desirable for all people planning a pregnancy. A genetics consultation helps future parents get rid of many worries and anxieties associated with the health of the child. Even in a practically healthy couple with no history of any genetic abnormalities, there is always a risk of having a child with pathologies, the difference is only a fraction of the probability.

The parents themselves or their close relatives have a diagnosis associated with genetic abnormalities. These can be diseases such as schizophrenia or other mental pathologies, Alzheimer's disease, Down's syndrome and many others. A mandatory indication for genetic analysis is the presence of a child already born by a couple or one of the spouses with a genetic anomaly.
When collecting an anamnesis, it turns out that a woman and a man have been unsuccessfully trying to conceive a baby for a long time (more than 1 year), while no pathologies are revealed by the gynecologist and andrologist.
Previous attempts to give birth to a child ended at different times, or the pregnancy froze, or the fetus was born unviable.
A risk factor is a pregnancy that occurs in a woman under the age of 18, and also if both or one of the parents have crossed the 40-year mark.
A genetics consultation is necessary if the spouses are related by blood.
Very often, deviations can be related to the work activity of one or both spouses. For example, if the nature of the work involves frequent interaction with harmful or toxic substances.
Genetic pathologies can be caused by the need for one of the spouses to take certain medicines. Usually these are potent drugs, for example, in diseases of the nervous system, mental disorders, oncological ailments.

The reason for consulting a geneticist is a suspicion of genetic thrombophilia. This disease is characterized by the formation of a large number of blood clots over a long period of time, which during pregnancy can provoke bleeding, miscarriage, and fetal fading.

Genetic analysis for congenital thrombophilia is prescribed in the presence of the following indications:

stroke or myocardial infarction before the age of 45 in relatives or in a history of a woman;
Varicose veins;
problems with pregnancy or intrauterine development of the fetus;
placental abruption in history.

The need for certain tests is determined purely individually and depends on the clinical picture.

Types of tests for genetic diseases in a couple

Pathologies can be detected by using various diagnostic methods. To obtain a reliable picture, a combination of several types of analyzes may be required.

Karyotype analysis or cytogenetic study

Karyotyping is carried out in order to determine the genome of the spouses, i.e. quantitative and qualitative composition of chromosomes. During life, the human karyotype does not change, so this analysis is done only once.

Deviation in the number of chromosomes from the norm in the direction of increase or decrease can confirm, for example, Down's syndrome and other hereditary diseases in parents. Including those that are asymptomatic, for example, Klinefelter's syndrome, Shereshevsky-Turner.

Karyotype analysis allows not only to determine the quantitative composition of chromosomes, but also to identify defects in their shape and size, as well as to diagnose breaks and other abnormalities. Such pathologies of the genome of even one of the spouses lead to the inability to bear a viable fetus or to complete infertility. In addition, damaged genes are the cause of the development of various serious diseases in the unborn child.

Karyotyping is prescribed in the following cases:

lag in sexual development of one of the future parents;
amenorrhea in girls over the age of 15;
earlier onset of menopause;
a history of spontaneous abortions in the early stages;
repeated unsuccessful IVF attempts;
the presence of consanguinity between the spouses;
the diagnosis of infertility in one of the spouses;
oligozoospermia or azoospermia in men.

For karyotyping, blood is taken from a vein, the analysis is taken on a full stomach.

These analyzes allow to reveal a wide range of hereditary diseases. In the course of molecular genetic diagnostics, a study of the features of the DNA structure is carried out.

This is an extensive and diverse group of methods designed to detect pathologies in the structure of a separate section of hereditary material in the form of an amino acid sequence. Thanks to such analyzes, a geneticist can diagnose such dangerous diseases as hemophilia, cystic fibrosis, hearing loss and many others.

The most popular among all molecular genetic methods is the diagnosis of PCR (polydimensional chain reaction). This is due to the high accuracy of the analysis results and the short lead times. In the course of the study, a certain section of DNA is selected, which, with the help of special preparations, is repeatedly duplicated.

Molecular genetic diagnostic methods are the most accurate in determining genetic diseases, and their results are recognized as the most informative.

The method is based on the fact that the DNA structure of any person does not change during life, while any cell of the body contains the same molecule. This makes it possible to use cells obtained from any part of the body for analysis: blood, buccal epithelium, hair, epidermal particles, etc. can be taken for the study.

The advantage of DNA analysis is that the defective gene can be detected before the onset of clinical symptoms of the disease, as well as in healthy people who are carriers of the gene mutation.

The disadvantage of the study is its rather high cost.

Watch the video about the consultation of a geneticist before planning a pregnancy:

Cytogenetic analysis

This type of study is based on the analysis of the structure of chromosomes using special microarrays that are applied to the DNA chips of lymphocytes isolated from the blood. Cytogenetic analysis is used quite rarely, because it takes a long time - the result becomes known only within a month.

But in the case of a woman's history of repeated episodes of miscarriage or a diagnosis of infertility, this type of study is the most informative. In addition, it helps to clarify the diagnosis in children in case of a suspected genetic disease.

Cytogenetic research helps to identify the following ailments:

Translocation of chromosomes, i.e. changes in their structure. Sometimes it is a hereditary pathology, but it can occur during fertilization or during the maturation of germ cells in both men and women.
Mosaicism of the sex chromosomes, i.e. pathological association of different genetic materials. Such an anomaly is a symptom of Klinefelter's syndrome, Turner's syndrome and other diseases.

FISH method (fluorescent hybridization)

This method is rarely used in Russian practice, although it has high sensitivity and accuracy. For analysis, a single chromosome or its segment is used, which are marked with special luminous markers to identify the area with defective genes.

Genetic tests are recommended for all couples planning to have a child, since gene mutations can occur even in apparently healthy people.

Very often, a person does not have any signs and symptoms of genetic pathologies, but at the same time he may be carriers of a defective gene.

If there are cases of hereditary pathologies in the family of at least one of the spouses, an appeal to a geneticist and a comprehensive examination is mandatory. These pathologies primarily include:

thrombophilia;
cystic fibrosis;
hearing loss;
hemophilia and many others.

Modern methods of molecular genetic studies of married couples make it possible to determine not only gene mutations and the presence of hereditary diseases, but also a predisposition to many severe pathologies at the genetic level.

These are diseases such as:

and other endocrine disorders;
atherosclerosis of cerebral vessels;
bronchial asthma;
oncological diseases;
osteoporosis and many others.

It is especially important to undergo a genetic examination for couples who decide to conceive a child in adulthood.

A person does not always have an idea about the state of health of his relatives and may not even suspect that he is a carrier of a damaged gene. Consulting a geneticist during pregnancy and conducting a genetic study in the early stages will help to avoid many risks for the mother and the unborn child, and will allow you to plan your pregnancy correctly.

Genetic analysis when planning pregnancy is a group of studies that helps determine the likelihood of having a child with genetic abnormalities and malformations. To genetics, as a science, the attitude changed from extremely negative to full recognition. But to this day, genetic studies are not the most common in preparation for conception. More often, a genetic analysis of a woman's blood is performed during pregnancy as part of a mandatory screening study. And in case of developmental anomalies identified during the time, presumably of a genetic nature.

Methods of genetic diagnostics can be non-invasive (clinical genetic modeling, ultrasound diagnostics and biochemical blood analysis) and invasive (amnio-, placento-, cordocentesis and chorion biopsy). All invasive methods carry some threat to the fetus, and involve the collection of material by puncture (needle puncture) and collection of material (amniotic fluid, placental cells or cord blood). Non-invasive methods are used for research for preventive purposes. Invasive - when verifying a diagnosis suggesting a serious chromosomal abnormality.

Mandatory genetic consultation

Voluntary visits to a geneticist are still rare. Most often, women or couples turn to genetics as part of a mandatory examination. Medical genetic counseling is considered mandatory if:

over 35 years old, and the future dad has reached the 40-year milestone;
both or one of the partners are under the age of 18;
the fetus was exposed to harmful factors (radioisotope irradiation, the action of toxic chemicals, or had been ill with viral infections, primarily rubella);
the family has children with congenital anomalies;
a woman has a history of two or more pregnancies that ended prematurely or stillbirth;
if in the family one or both parents have relatives with chromosomal abnormalities;
the child was conceived in a closely related relationship;
the woman was at risk by passing a blood test or undergoing an ultrasound examination.

If the couple is presumably healthy, the parents-to-be can simply talk to a geneticist who will ask them about their relatives and talk about the possible risks. If the results of the examination revealed high risks of the birth of children with anomalies, a consultation with a geneticist is required.

Genetic blood test

A blood test for genetics is a whole group of studies. Unfortunately, if even very low risks are detected, these examinations do not give a 100% guarantee of the birth of completely healthy offspring. But they allow us to identify cases where the risk of giving birth to sick children, children with deformities and unviable fetuses is very high. It is better to do this as early as possible in order to avoid problems associated with caring for handicapped children and the loss of a child of the 1st year of life. The most informative methods are considered to be:

DNA diagnostics of specific diseases, such as phenylketonuria;
karyotyping;
HLA typing.

The first methods are used if the family has cases of specific ailments (cystic fibrosis, phenylketonuria, and others). The latter are designed to diagnose the risk of developing chromosomal abnormalities in offspring (Edwards, Down, Lenezh, Patau and others syndromes). The latest methods are designed to identify the causes of infertility, incompatibility of spouses in terms of genetics, these methods are used before IVF.

If the risk of developing chromosomal abnormalities is high, then the woman will need to be monitored by a geneticist during the entire pregnancy process. In some cases, if a blood test was taken as part of a mandatory screening study already during the gestation period, with high risks of having children with anomalies, a woman may be recommended invasive examination methods to confirm the diagnosis. And termination of pregnancy, if the diagnosis is confirmed.

Genetics, a young and very promising science, revolves around a lot of speculation, fears and excessive expectations. This was largely the result of the efforts of the American film industry, popular in the world, whose fantastic images have long become part of modern popular culture: ninja turtles, spiderman, catwoman - all these creatures gained superpowers thanks to a genetic experiment or a successful genetic "failure". Thousands of young people are raving in fantasies where they wield powerful powers resulting from a genetic disorder. The reverse media side of the image are pictures of monstrous monsters, victims of unsuccessful genetic experiments. Their destiny is to pose a threat to all living things, to be an adversary for the superhero of the next Hollywood blockbuster.

In fact, genetics is not at all omnipotent, it is not yet able to give a person what he dreams of, but it can bring benefits now.

Genetic analysis when planning pregnancy is an opportunity for young couples to look a little into the future, to anticipate the physical and mental development of their child.

About genetics

The term "genetics" comes from the Greek word "γενητως" - to generate, to descend from someone. Genetics studies the laws of transmission of biological information (heredity) from generation to generation, as well as the process of changing this information under the influence of one or another factor.

Modern genetics is the possibility of curing previously incurable diseases, improving the capabilities of living organisms (eugenics), developing uninhabitable territories, solving the problem of garbage and ecology in general. They began to count on genetics as a means capable of advancing the interests of mankind in the distant future.

Basic terminology of genetics

Biological information is transmitted using DNA and RNA macromolecules - complex organic formations consisting of blocks of nucleotides. The part of DNA or RNA that is responsible for making a particular kind of protein is called a "gene". Genes are folded into alleles (they determine the order and sequence of creation of protein formations).

DNA and RNA molecules are stored in chromosomes - special biological structures contained in eukaryotic cells. The interior of a chromosome is called chromatin.

Each biological species has a limited number of chromosomes. For example, a person has 46 of them, a dog has 68, a turkey has 82, and a fruit fly has 8. The chromosome of every living creature, even of the same species, has its own unique features in shape, outline, and size. These features are so characteristic that they can easily identify a specific biological individual, which, by the way, is successfully used by forensic experts. To denote the uniqueness of the chromosome set of each individual, the Soviet scientist G.A. Levitsky coined the term "karyotype". Later, medical science learned to determine the norm, anomalies and pathologies of the gene set by the karyotype. A visual representation of the chromosome set is called "karyogram". It is she who serves as the starting point for human genetic analysis, including pregnancy planning.

Genetic abnormalities in WHO data

Genetic anomalies are morphofunctional disorders in the body resulting from gene and chromosomal mutations.

Of extreme concern are the WHO data on the health of the millennials. According to the statistics of European medical institutions, only 14% of secondary education graduates can be considered healthy.

Bad ecology, various addictions, unreasonable lifestyle have led to a significant increase in the number of newborns with genetic disorders. The number of such children reaches 17%. Meanwhile, studies conducted by WHO experts indicate that already at the figure of 10%, the degeneration of the human species begins. This, no doubt, cannot but cause concern among the sane part of society.

Thus, the control of genetic health is the way to the improvement of society as a whole!

About the benefits of karyotyping in pregnancy planning

A woman has to take a variety of tests when planning a pregnancy, some of them are mandatory, and some are not. Karyotyping - the so-called genetic tests when planning a pregnancy - is not a mandatory procedure, but can be important, if not decisive, importance.

Consultation with a geneticist

A consultation with a geneticist involves questioning the couple. In the questionnaire, they must provide information about:

past and chronic diseases;
your lifestyle;
lifestyle of the next of kin;
their state of health and the health of close relatives.

This information will help the specialist to navigate when making a prognosis for the development of the unborn child. If the doctor decides that there are grounds for a more detailed analysis, a referral for a cytological study will be given (based on the results of which karyograms of future parents are compiled). The future father will also have to hand over the sperm for analysis to compile a spermogram. The analysis will determine the presence of possible genetic pathologies in the sperm of a man. It is also recommended that spouses take an immunocompatibility test (HLA - typing). This type of analysis allows you to determine the presence of leukocyte compatibility of the pair. That is, in other words, whether the spouses are allergic to each other. An important moment for a young family, otherwise they are threatened with infertility and the impossibility of conception.

At-risk groups

The risk of genetic incompatibility has three ratings:

positive - the couple will have a healthy and strong child;
satisfactory - there is a slight risk of developing pathologies in the fetus. There is a danger that the child will be born unhealthy and will have physiological and mental abnormalities. Women in this risk category should be constantly under the supervision of a doctor during pregnancy;
unsatisfactory - if this score is set, then pregnancy planning should be abandoned, since there is a high probability of having a child with serious pathologies. In such a sad case, pregnancy can be accompanied by very strong toxicosis that can kill not only the fetus, but also the woman herself.

There are a number of reasons that are a weighty argument for taking a blood test for karyotyping:

close relatives had diseases of a hereditary nature - schizophrenia, hemophilia, phenylketonuria, color blindness, Tay-Sachs syndrome, Down syndrome, Joubert syndrome, Turner syndrome, Prader-Willi syndrome, neurofibromatosis, cystic fibrosis and others;
already born children have genetic abnormalities;
a young, healthy couple for a long time (1-2 years) cannot conceive a child;

in the medical history of the expectant mother, cases of miscarriage, anembryony (fetal egg without an embryo) or the birth of a dead child are recorded;
the age of the future female parent is less than 18 or more than 35 years old, male - more than 40 years old;
spouses are relatives by blood;
the work of one or the other future parent takes place in harmful conditions, for example, in contact with harmful substances, radiation that can affect the genetic characteristics of a person;
the future parent is taking medications that can harm the fetus or change its development.