Karyotyping of parents. Having trouble getting pregnant? Karyotype analysis: what is it?

How is diagnostics carried out?

Material for research any dividing cells can act, derived from the epidermis, bone marrow, through the placenta (during the development of the fetus in the womb), but more often from the blood (lymphocytes).

• Venous blood is collected from the patient, which is placed in a test tube and sent to the laboratory for testing.
• Lymphocytes are separated from the resulting material, placed in a test tube, and a substance (mitogens) is added that causes them to actively divide.
• Then another substance (colchicine) is added to stop cell division at the metaphase stage.
• The results obtained are recorded, stained with a special solution (dye) and photographed. The entire procedure is carried out under a microscope.
• From the set of photographs obtained, a karyotype or a numbered set of homologous chromosomes is formed. Having arranged them in pairs, the specialist analyzes them.

Preparing for the study

Diagnostics does not require special training . At the same time, the patient needs to understand that the procedure is performed only once in a lifetime, since the karyotype does not change over time. Therefore, experts advise adhering to some rules before taking the test:

• It is not recommended to donate blood on an empty stomach, unlike many other types of research.
• For 3-4 weeks, the use of antibiotics is excluded.
• Be sure to get a good night's sleep the night before the test and eliminate the influence of stressful situations.

Indications for the procedure

Genetic diagnostics can be performed if there are certain medical indications or without them (at the request of the spouses).

Indications for diagnostics:

• Unsuccessful pregnancy in women, repeated several times in a row for no apparent reason (fetal fading, miscarriage).
• Suspicion of infertility of the father or mother (both spouses, regardless of gender).
• Intrauterine fetal death.
• The birth of a child with serious hereditary diseases, developmental anomalies.

What can a karyotype determine?

The results of the study may show:

• The risk of having a child with pathologies in development (when studying the karyotype of spouses).
• Cause of congenital childhood anomaly ( mental retardation, ZPR).
• Recognition chromosomal diseases fetus (Down syndrome, Patau and others).

Using karyotyping, you can clearly trace the structure of the chromosome set and identify:

• Reversal of a chromosomal region (inversion).
• Loss of a section of a chromosome or deletion.
• The presence of an extra 3rd chromosome in a pair (trisomy), which occurs in Down syndrome.
• Duplication of a fragment in a chain (monosomy).
• Movement of sections in the structure of chromosomes (castling).

What can't it show?

Despite the depth of the analysis, it will not be able to recognize some deviations from the norm, namely:

• The position of any individual genes in the DNA chain.
• Exact number of genes in chromosomes.
• Minor gene mutations which caused fetal pathology.

Analysis results

The standard results are:

• * 46, XY, which corresponds to a normal male karyotype.
• * 46, XX, which corresponds to a normal female karyotype.

Such values ​​also apply to the study of children according to the sex of the child. The specialist records any other options according to the form of the international cytogenetic nomenclature and makes a decoding based on accepted values, for example: 47, XX,+21; 47,XY,+21 ( developing disease Down in the fetus - Trisomy on the 21st chromosome), 47, XX, +13; 47, XY,+13 (Patau syndrome in the fetus), etc.

Where to do the analysis?

Karyotyping - expensive and time-consuming process. In district clinics it will not be possible to donate blood for this test due to the lack of special specialists and equipment. Diagnostics can be carried out in family planning centers, genetic institutes, general laboratories, mother and child centers, some modern clinics.

• In Moscow the service is provided by: Invitro, Family clinic Dr. Anna, VitroClinic, CMD Center for Molecular Diagnostics, CIR Laboratory, Center for Maternal and Child Health named after V.I. Kulakova, Center for Fetal Medicine and others.
• IN St. Petersburg The service is provided by: Genesis Reproduction Center, Mother and Child Clinic, EmbryLife Reproductive Technologies Clinic, Mother and Child Clinic, Invitro, Ava-Peter Clinic and others.

Price and lead time for analysis

Karyotyping refers to expensive diagnostic methods. approximate cost:

• Study of the karyotype of one patient (blood with heparin) - 4500-7500 rubles.
• Taking a blood test for a karyotype with photographs of chromosomes costs 5,000-8,000 rubles.
• Karyotyping with detection of aberrations (blood with heparin) is a more informative analysis, but its cost is more expensive - from 5500-6000 rubles.
• Karyotyping with identification of aberrations with photographs of chromosomes - from about 6,000 rubles.

The deadline for preparing the analysis must be clarified at the place where the diagnostics will be carried out. Usually it ranges from 14 to 28 days (excluding the day the material was taken).

A blood karyotype test is an important modern diagnostic procedure. It allows you to accurately assess the number and structure of chromosomes in the human body. This will help find out the reasons congenital anomalies in the fetus and genetic hereditary diseases.

Karyotype analysis is a modern laboratory test that allows us to identify possible pathological disorders at the genetic level, establish the cause of infertility, and even determine whether the unborn child will be healthy. The resulting result records changes in the set of chromosomes. Diagnostic procedure is currently in great demand because it makes it possible establish the level of genetic matching between men and women.

Karyotype - chromosome set, distinguished by certain characteristics. The norm is the presence of 46 chromosomes:

• 44 – responsible for resemblance to parents (eye color, hair, etc.).
• 2 – indicate gender.

Karyotyping analysis is necessary to determine pathological disorders occurring in the body. Laboratory diagnostics are indispensable for establishing the causes of infertility and the presence congenital pathologies, which can be inherited.

Sequence of karyotyping:

1. Collection of venous blood and screening of mononuclear leukocytes in the laboratory.
2. Placement of biological material in a medium with PHA (phytohemagglutinin) and the beginning of cell cultivation (mitotic division).
3. Termination of mitosis after reaching the metaphase stage, which is carried out with the help of colchicine.
4. Treatment with a hypotonic solution and production of microslides.
5. Studying and photographing the resulting cells using a special microscope.

Only after 2 weeks, specialists in a laboratory receive the result of the study. The form contains information on total number chromosomes, and existing violations of the genetic code are recorded.

Appointed genetic research for the purpose of assessment reproductive functions couples planning children. To make a diagnosis, a complete picture of genetic characteristics is necessary. Based on the results obtained, you can look for ways to solve the existing problem, if any. Karyotyping is aimed at determining the number, shape and size of chromosomes in a biological sample.

If there are any violations, there are problems on the part of internal systems and organs. In some cases completely healthy people are carriers of a genetic mutation. It is not possible to determine this visually. The result is problems with conception, developmental defects or the birth of an unhealthy child.

The following medical indications exist for karyotyping:

• age limit of 35 years and older;
• termination of pregnancy and infertility;
• hormonal disorders in female body;
• exposure to radiation or chemical poisoning;
• polluted environment and the presence of bad habits;
• hereditary predisposition and consanguinity;
• the presence of chromosome mutations in previous children.

A blood test for karyotype should be performed once, since these characteristics do not change with age. The absolute indication for karyotyping is the problem of conception and the inability to carry a pregnancy to term. IN last years More and more young couples are taking this test to ensure that their children are born healthy. Laboratory diagnostics makes it possible to assess the likelihood of a baby being born with abnormalities caused by chromosomal abnormalities and to identify the true cause of infertility.

Preparation for karyotyping

Blood cells are used for karyotyping, so before taking the test you need to prepare by eliminating the influence of third-party factors that complicate their growth. Otherwise, the research conducted will be poorly informative.

Preparation must begin 2 weeks in advance:

1. Eliminate alcohol, smoking and harmful foods.
2. Discuss stopping drug therapy with your doctor.
3. 9-11 hours before collecting biological material, avoid eating.
4. 2-3 hours before laboratory research do not drink liquid.

Blood donation for karyotype is carried out in the morning on an empty stomach. In case of deterioration of health, infectious disease or exacerbation of chronic diseases, the study is postponed until the patient recovers.

• Aneuploidy (change in quantity). In case of poor quality biological material Difficulties may arise during the diagnostic process.
• Structural deviations - connected combinations after separation. The study reveals major violations. In order to identify minor deviations, microarray chromosomal analysis is prescribed.

Types of diagnostics

Karyotyping is carried out in several ways, which differ in the approach to research and sources of biological material:

1. Classical– venous blood (10-20 ml) is taken for examination. In pregnant women, amniotic fluid may need to be collected for diagnosis. In some cases, the cells are taken from the bone marrow. Chromosomes are stained and examined using light microscopy.
2. SKY (spectral) – new technique, which is considered to be the most effective, because it allows you to clearly and quickly identify violations. In this case, parts of chromosomes are detected using fluorescent tags without culturing cells. Used when standard karyotyping has failed.
3. FISH analysis (fluorescence hybridization)– the study is carried out in a special way and involves the specific binding of certain sections of chromosomes and fluorescent labels. For laboratory diagnostics, embryonic cells or ejaculate are collected.

To obtain the most accurate result, a blood test is carried out in conjunction with other, no less informative, genetic tests.

How to decrypt

The diagnosis is made based on the karyotyping result obtained by a geneticist. The specialist conducts a thorough analysis and makes a conclusion indicating the reasons for reproductive disorders or the birth of an unhealthy child.

Decoding the analysis allows us to determine the following genetic disorders:

• the presence of genetically different cells;
• movement of sections of genetic code;
• reversal or doubling of a chromosome;
• the absence of one fragment or the presence of an extra one.

Using karyotyping, it is possible to establish a predisposition to the development of hypertension, arthritis, myocardial infarction, stroke and diabetes. Thanks to this analysis, thousands of married couples have identified the cause of infertility and successfully recovered from existing disorders in the body.

Deviations are possible on both the male and female sides. Normal indicators:

• for men - 46XY;
• for women - 46XX.

In children, the following violations of the genetic code are observed:

1. 47XX+21 or 47XY+21 – Down syndrome (presence of an extra chromosome).
2. 47XX+13 or 47XY+13 – Patau syndrome.

There are other deviations from the norm that are less dangerous. Only a geneticist can calculate the risks of having an unhealthy child for each individual case. If karyotyping revealed dangerous violations or mutations, the doctor recommends termination of pregnancy.

Karyotyping assesses not only the number, but also the state of genes:

• Mutations that cause thrombus formation, disrupting the nutrition of small vessels at the time of placenta formation, which causes miscarriages.
• Pathologies from the cystic fibrosis gene, in order to exclude the likelihood of developing a certain disease in a child.
• Gene disorders on the Y chromosome.
• Deviations in genes that are responsible for the ability to disinfect toxic factors.

If a deletion (loss of a section) is detected in the Y chromosome, we are talking about male infertility due to impaired spermatogenesis. This is the cause of hereditary diseases.

What to do if deviations are found

To exclude the possibility of genetic abnormalities in a child, the karyotype of both parents should be checked before conception. If there are genetic disorders, the doctor will explain possible risks. Don't panic when you discover chromosomal mutations. Even in this case, you can carry the pregnancy to term and give birth to a healthy child if a child is found, following the doctor’s recommendations.

Child planning allows you to prepare the body of the mother and father for the birth of healthy offspring and determine the risks of having unhealthy children. Even after a woman becomes pregnant, karyotyping can be done in the first week to assess possible risks, which allows timely measures to be taken to prevent miscarriage. In the presence of serious genetic mutations, the decision to terminate the pregnancy is made by the married couple. The doctor only points out possible consequences and makes recommendations when interruption is necessary.

Conclusion

Genetics currently represents a highly developed scientific field. With the help of modern diagnostic tests deviations can be identified initial forms progression and take measures to combat them. Thanks to karyotyping, it is possible to cure infertility, prevent repeated miscarriages and eliminate the likelihood of having children with a genetic mutation. When planning a family, it would not be superfluous to check for genetic compatibility.

Karyotyping is an analysis to identify chromosomal abnormalities, which is carried out to determine abnormalities in the number and structure of chromosomes. This research method can be included in the general list of examinations that are prescribed to couples before planning conception. Its implementation is an important part of the diagnosis, since the results make it possible to identify chromosomal abnormalities that interfere with conception, pregnancy and cause severe abnormalities in the development of the fetus.

For karyotyping analysis, both venous blood (sometimes bone marrow or skin cells) of the parents and fragments of the placenta or amniotic fluid can be used. It is especially important to carry out these when high risks transfers chromosomal pathologies to an unborn child (for example, if one of the relatives is diagnosed with Edwards, Patau, etc.).

What is a karyotype? Who should undergo karyotyping? How is this analysis carried out? What can it reveal? You will get answers to these and other popular questions by reading this article.

What is a karyotype?

A karyotype is a set of chromosomes in a human cell. Normally, it includes 46 (23 pairs) of chromosomes, 44 (22 pairs) of them are autosomal and have the same structure in both male and female bodies. One pair of chromosomes differs in structure and determines the sex of the unborn child. In women it is represented by XX chromosomes, and in men it is represented by XY chromosomes. The normal karyotype in women is 46, XX, and in men - 46, XY.

Each chromosome consists of genes that determine heredity. Throughout life, the karyotype does not change, and that is why you can take an analysis to determine it once.

The essence of the method

To determine the karyotype, a culture of cells taken from a person is used, which is studied in vitro (i.e., in a test tube). After the necessary cells (blood lymphocytes, skin cells or bone marrow) are isolated, a substance is added to them for their active reproduction. Such cells are kept in an incubator for some time, and then colchicine is added to them, which stops their division in metaphase. After this, the material is stained with a dye that clearly visualizes chromosomes and examined under a microscope.

Chromosomes are photographed, numbered, arranged in pairs in the form of a karyogram, and analyzed. Chromosome numbers are assigned in descending order of size. Last number assigned to sex chromosomes.

Indications

Karyotyping is usually recommended at the stage of conception planning - this approach helps minimize the risk of having a child with hereditary pathologies. However, in some cases, this analysis becomes possible after pregnancy. At this stage, karyotyping makes it possible to determine the risks of inheriting a particular pathology or is performed on fetal cells (prenatal karyotyping) in order to identify an already inherited developmental abnormality (for example, Down syndrome).

• the age of the spouses is over 35 years;
• the presence in the family history of a woman or man of cases of chromosomal pathologies (Down syndrome, Patau, Edwards, etc.);
• prolonged absence of conception for unknown reasons;
• planning;
• previously performed unsuccessful IVF procedures;
• bad habits or taking certain medications by the expectant mother;
• hormonal imbalance in women;
• frequent contacts with ionizing radiation and harmful chemicals;
• women have a history of spontaneous abortion;
• history of stillbirth;
• the presence of children with hereditary diseases;
• history of episodes of early infant mortality;
• caused by disturbances in sperm development;
• marriage between close relatives.

• fetal development abnormalities;
• deviations of psychomotor or psycho-speech development in combination with microanomalies;
• congenital malformations;
• mental retardation;
• growth retardation;
• deviations in sexual development.

How is the analysis carried out?

• drinking alcohol;
• taking some medicines(especially antibiotics);
• spicy infectious diseases or exacerbation of chronic pathologies.

Blood sampling from a vein for analysis is performed in the morning when the patient is well-fed. It is not recommended to donate biomaterial on an empty stomach. When collecting tissue samples for fetal karyotyping, sampling is carried out under ultrasound guidance.

How long to wait for the result?

The result of karyotyping can be obtained 5-7 days after submitting the material for research. During this time, specialists observe cell division in the incubator, inhibit their development at a certain point, analyze the resulting material, combine the data into a single cytogenetic scheme, compare it with the norm and draw up a conclusion.

What can karyotyping reveal?

The analysis allows you to determine:

• shape, size and structure of chromosomes;
• primary and secondary constrictions between paired chromosomes;
• heterogeneity of areas.

The results of karyotyping according to the generally accepted international scheme indicate:

• number of chromosomes;
• belonging to autosomes or sex chromosomes;
• structural features of chromosomes.

Karyotype examination allows us to identify:

• trisomy (or the presence of a third chromosome in a pair) - detected in Down syndrome, with trisomy on chromosome 13, Patau syndrome develops, with an increase in the number on chromosome 18, Edwards syndrome occurs, with the appearance of an extra X chromosome, Klinefelter syndrome is detected;
• monosomy – absence of one chromosome in a pair;
• deletion – lack of a section of a chromosome;
• inversion – reversal of a chromosome section;
• translocation – movement of chromosome sections.

Karyotyping allows you to identify the following pathologies:

• chromosomal syndromes: Down, Patau, Klinefelter, Edwards;
• mutations that provoke increased thrombus formation and premature termination of pregnancy;
• gene mutations, when the body is unable to detoxify (neutralize toxic agents);
• changes in the Y chromosome;
• tendency to and;
• tendency to.

What to do if deviations are detected?

When detecting abnormalities in the karyotype, the doctor explains to the patient the features of the detected pathology and talks about the nature of its impact on the child’s life. Particular attention is paid to incurable chromosomal and gene abnormalities. The decision on the advisability of continuing the pregnancy is made exclusively by the parents of the unborn baby, and the doctor only provides the necessary information about the pathology.

If a tendency to develop certain diseases (for example, myocardial infarction, diabetes mellitus or hypertension) is identified, attempts may be made to prevent them in the future.

Karyotyping is the analysis of a person's chromosome set. This test is done by examining lymphocytes in the blood, bone marrow cells, skin, amniotic fluid, or placenta. Its implementation is indicated at the stage of planning conception, but if necessary, the analysis can be carried out during pregnancy (on samples of cells from the parents or fetus) or on an already born child. Karyotyping results allow us to detect the risk of developing chromosomal and genetic pathologies and identify predisposition to certain diseases.