Karyotype analysis. Karyotype study

One of the most modern diagnostic methods is a genetic blood test. This study allows you to identify a person's predisposition to the development of various hereditary diseases. An analysis for a karyotype reflects changes in a person's chromosome set. The study is very much in demand today, as it allows you to determine the discrepancy in the sets of chromosomes of the husband and wife before conceiving a child.

Definition

What is a karyotype? This is the set of chromosomes of each person. Each person has an individual set of chromosomes, which may vary in their number, size and shape, and other characteristics. Normally, the number of chromosomes is 46. 44 of them are responsible for the external similarity of the parents and the child. They determine the color of the hair, eyes, skin, the shape of the ears and nose, and so on. Only 2 chromosomes are responsible for sex.

When to take a test

Karyotyping is done only once in a lifetime, because the set of chromosomes and their characteristics cannot change with age. This study is assigned to spouses with problems with conceiving and bearing a child.

Today, young people are increasingly taking this test on their own before planning a pregnancy.

A feature of genetic analysis for a karyotype is to assess the risks of having a baby with genetic abnormalities and diseases. Also, the analysis can reveal the causes of miscarriage or infertility of one of the spouses.

Medical indications for the study are:

• The age of one of the spouses is more than 35 years old when planning pregnancy.
• Inability to conceive a child for unknown reasons.
• Ineffective IVF operations.
• The presence of a genetic disease in a husband or wife.
• Hormonal failure in a woman.
• Failure in the maturation of spermatozoa.
• Accommodation in an unfavorably ecological area.
• Chemical poisoning or exposure of one of the spouses.
• Bad habits in a woman.
• Multiple miscarriages.
• Marriages between relatives.
• Having a child with a genetic disorder.

How the study is done

Preparation for analysis is not difficult for patients. Karyotype analysis is not carried out on an empty stomach; you can eat before blood sampling. It is only necessary to stop taking antibiotics 7 days before the sampling. Blood is taken from the patient's vein. After that, with the help of special equipment, mononuclear leukocytes are eliminated from the blood. After that, cells capable of dividing are introduced into the blood. At a certain stage, the specialist evaluates the result, photographs it and makes an opinion.

Usually, the result of the karyotype analysis can be obtained no earlier than 14 days later.

The form from the laboratory will contain information about the number of chromosomes in the patient and their deviations in various parameters, if any.

Many couples are interested in where to take a karyotype test. If the analysis is prescribed for you by a doctor, you can do it at a family planning center. You can also apply there for voluntary research. In addition, the analysis is done at the institutes of genetics and other specialized institutions. The local clinic does not provide this service. The cost of analysis can vary from 5000 to 8000 rubles. depending on the completeness of the information.

How to decrypt

Only a geneticist can decipher the analysis. The results of the analyzes of a married couple are carefully analyzed. After that, the doctor can give an opinion about the causes of your problems with conceiving or about the risks of having a child with abnormalities. What can modern karyotype analysis show? The breakdown of the analysis shows the following risks and deviations:

• Mosaicism.
• Translocation assessment.
• The absence of one of the fragments of the chromosome.
• Absence of one of the paired chromosomes.
• The presence of an extra chromosome.
• The unfolding of one of the fragments of the chromosome chain.
• Gene mutations that lead to abnormalities in the newborn.

In addition, depending on the karyotype, it is possible to determine a person's predisposition to such diseases as:

• Myocardial infarction.
• Stroke.
• Diabetes.
• Hypertension.
• Arthritis, etc.

As a result, the norm is 46XY in men, 46XX in women. In children, the possible deviations are as follows:

• 47XX + 21 and 47XY + 21 - the child has an extra chromosome in the 21st pair, which is evidence of Down syndrome.
• 47XX + 13 and 47XY + 13 - such children are born with Patau syndrome.

There are a number of other deviations. Some of them are dangerous, others not so much. Only a doctor can determine the real risks of having an unhealthy child in each individual case. If dangerous mutations are detected, it is better to terminate the pregnancy.

What to do if deviations are found

In order to prevent the birth of a child with gene mutations, it is better to donate blood for analysis even before pregnancy. This is especially true for those couples in which the wife or husband is over 40 years old.

If abnormalities are found, the doctor will explain the risks to you.

When the test is done on a woman who is already pregnant, if a gene disorder is found, the woman may be asked to terminate the pregnancy. However, the decision to give birth or not remains with the parents. No one has the right to insist on an abortion. However, you should not immediately panic if you have gene disorders. Many of them do not affect the health of the child. With such anomalies, you just need to carefully monitor the pregnancy and follow all the doctor's recommendations.

Every married couple should carefully plan the birth of children. If for some reason you are assigned an analysis to determine the karyotype, you must definitely do the indicated test. It is better to donate blood for research even before pregnancy or in the first weeks after conception. Parents should not be faced with the question of how much the analysis costs, because the birth of a healthy child is much more expensive than any money.

In contact with

In the generally accepted sense, a family is loving parents and happy children, so it is very important to create excellent conditions for the birth and upbringing of babies.

Due to various circumstances, many modern young people have problems conceiving children, most often this is due to genetic incompatibility. Thanks to modern technologies and unique equipment, today it is possible to conduct a special analysis that will reveal the percentage of parental compatibility, as well as possible genetic abnormalities.

This procedure is called karyotyping, once in a lifetime you donate the necessary genetic material, and with the help of special manipulations, the chromosome set of a married couple is established.

Using the results of this analysis, it is easy to establish the probability of having children in spouses, as well as to identify the possibility of a child acquiring hereditary genetic diseases. To date, this research method has almost a hundred percent result, which to a large extent allows you to simultaneously identify several reasons for the absence of pregnancy in a woman. Such procedures are absolutely painless, but require special preparation under certain circumstances. The desire to have healthy offspring is inherent in every married couple, so hundreds of thousands of people undergo karyotyping every year.

Main reasons for analysis

Karyotyping is a fairly well-known procedure in Western and European countries, but in Russia this analysis is carried out not so long ago, although the number of applicants increases every year.

The main task of this analysis is to identify compatibility between parents, which will allow you to conceive and give birth to offspring without pathologies and various kinds of abnormalities.

As a rule, such an analysis is carried out in the first stages, although it is possible to carry out the procedure in a pregnant woman. In such a situation, the necessary material is also taken from the fetus to determine the quality of the chromosome set. Of course, karyotyping is not a mandatory procedure for young parents, although it will allow you to identify a lot of abnormalities in an unborn baby.

During the analysis, it is possible to establish the predisposition of the unborn baby to diabetes mellitus and hypertension, heart attacks and various pathologies of the heart and joints. During the sampling, a defective pair of chromosomes is detected, which allows you to calculate the risk of giving birth to a non-full-fledged baby.

Indications

There are certain categories of citizens who just need to go through a similar procedure, today this number includes:

• Parents over the age of 35, even if this rule applies to only one of the spouses.
• Infertility, the causes of which have not been previously identified.
• Unsuccessful in vitro fertilization options.
• Hereditary diseases in parents.
• Problems with hormonal balance in the fair sex.
• Unidentified causes of violation of ejaculation and qualitative activity of spermatozoa.
• Bad environment and work with chemicals.
• Lack of a healthy lifestyle, smoking, drugs, alcohol, use of medications.
• Previously recorded abortion, miscarriage, premature birth.
• Marriages with close blood relatives, as well as previously born children with genetic abnormalities.

What the analysis reveals

For the procedure, a unique blood sampling technology is used, which allows you to separate the blood cells and isolate the genetic chain. A geneticist can easily find out the percentage of the risk of trisomy (Down syndrome), the absence of one chromosome in the chain (monosomy), the loss of a genetic site (a deletion, which is a sign of male infertility), as well as duplication, inversion and other genetic abnormalities.

In addition to determining these deviations, various kinds of anomalies can be established, which can lead to serious deviations in the development of the fetus, causing a gene mutation responsible for the formation of blood clots and detoxification. Timely detection of these deviations will create normal conditions for the development of the fetus and prevent miscarriages and premature births.

How to submit? Preparation for analysis

This analysis is carried out in the laboratory and is absolutely safe for men and women, if the woman is pregnant, the analysis is also performed on the existing fetus. Blood cells are taken from the parents and, through various manipulations, the chromosome set is isolated, then the quality of the existing chromosomes and the number of gene deformations are determined.

If you have made a decision and are ready to undergo the karyotyping procedure, you must stop using tobacco products, alcoholic products and medicines within two weeks. In case of exacerbation of chronic and viral diseases, it is necessary to postpone the blood sampling procedure to a later period. The whole procedure is carried out within five days, lymphocytes are isolated from the biological fluid during the period of division. Within 72 hours, a complete analysis of cell reproduction is carried out, which allows drawing conclusions about the pathologies and risks of miscarriage.

Thanks to unique technologies, only 15 lymphocytes and various preparations are required to obtain accurate results, which means that you do not have to donate blood and other body fluids several times. For one married couple, it is enough to conduct only one analysis, with which you can plan pregnancy and the birth of healthy babies.

There are situations when pregnancy has already begun, and the necessary tests to identify abnormalities have not been carried out, so the genetic material is taken from the fetus and both parents.

It is best to carry out the analysis in the first trimester of pregnancy, at this stage of fetal development it is easy to establish diseases such as Down syndrome, Turner and Edwards, as well as other complex pathologies. In order not to harm the unborn baby, tests are carried out as follows:

• Invasive method
• non-invasive method

A non-invasive method is considered a safe way to obtain results, which involves an ultrasound scan, as well as blood sampling from the mother to determine various markers.

The most accurate results can be obtained when analyzing the invasive method, but it is quite risky. Special equipment is used to perform manipulations in the uterus, which allow obtaining the necessary genetic material.

All procedures are painless for the woman and the fetus, however, after passing the analysis by an invasive method, inpatient observation is required for several hours. This procedure can cause a threatened miscarriage or missed pregnancy, so doctors talk in detail about all the consequences and possible complications.

What to do if deviations are found?

After receiving the results, the geneticist prescribes, during which he talks in detail about the probabilities of having a handicapped child. In the event that the compatibility of the parents is impeccable, and the chromosome set has no deviations, young parents are told all the stages of pregnancy planning.

If various deviations are identified, then the doctor prescribes a course of treatment with which you can avoid some troubles when planning a pregnancy. However, if abnormalities are identified during pregnancy, parents are advised to terminate the pregnancy or leave them the choice.

In this situation, you can easily take a chance and give birth to a full-fledged healthy child, but the doctor is obliged to warn about all possible deviations and their consequences. At the stage of planning a baby, you can use donor genetic material. A geneticist and a gynecologist do not have legal grounds for coercion to remove a pregnancy, so the choice always remains with the parents.

Children are the most important thing that a person can have, you should be extremely careful in the process of planning and conception. Fortunately, with the help of the karyotyping procedure, troubles can be avoided during the development of the fetus.

Karyotyping is an analysis to detect chromosomal abnormalities, which is carried out to determine abnormalities in the number and structure of chromosomes. This research method may be included in the general list of examinations that are assigned 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 analysis for karyotyping, both venous blood (sometimes cells of the bone marrow or skin) of the parents, and fragments of the placenta or amniotic fluid can be used. It is especially important to perform these at high risks of transmitting chromosomal pathologies to an unborn child (for example, if one of the relatives is diagnosed with Edwards, Patau, etc.).

What is a karyotype? Who is eligible for karyotyping? How is this analysis done? What can he reveal? You will receive 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, both in the male and in the female body. One pair of chromosomes differs in its structure and determines the sex of the unborn child. In women, it is represented by XX chromosomes, and in men - XY. The normal karyotype in women is 46,XX, and in men it is 46,XY.

Each chromosome is made up 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 examined in vitro (i.e., in vitro). After the selection of the necessary cells (blood lymphocytes, skin cells or bone marrow), 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 that, the material is stained with a dye that visualizes the chromosomes well, 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 their size. The last number is assigned to the sex chromosomes.

Indications

Karyotyping is usually recommended at the stage of conception planning - this approach minimizes the risk of having a child with hereditary pathologies. However, in some cases, this analysis becomes possible after the onset of pregnancy. At this stage, karyotyping allows you 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 anomaly (for example, Down syndrome).

• spouses are over 35 years of age;
• the presence in the family history of a woman or a man of cases of chromosomal pathologies (Down syndrome, Patau, Edwards, etc.);
• prolonged absence of conception for unexplained reasons;
• planning;
• previously performed unsuccessful IVF procedures;
• bad habits or taking certain medications in a future mother;
• hormonal imbalance in a woman;
• frequent contact with ionizing radiation and harmful chemicals;
• the presence in the anamnesis of women of spontaneous abortions;
• stillborn child in history;
• the presence of children with hereditary diseases;
• episodes of early infant mortality in history;
• caused by disorders in the development of spermatozoa;
• marriage between close relatives.

• anomalies in the development of the fetus;
• 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?

• alcohol intake;
• taking certain medicines (especially antibiotics);
• acute infectious diseases or exacerbation of chronic pathologies.

Blood sampling from a vein for analysis is performed in the morning in a state of satiety of the patient. It is not recommended to take biomaterial on an empty stomach. When taking tissue samples for fetal karyotyping, sampling is performed under ultrasound guidance.

How long to wait for the result?

The result of karyotyping can be obtained 5-7 days after the delivery of the material for research. During this time, specialists monitor cell division in the incubator, slow down their development at a certain point, analyze the material obtained, 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;
• site heterogeneity.

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

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

The study of the karyotype allows you to identify:

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

Karyotyping can detect the following pathologies:

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

What to do if deviations are detected?

When abnormalities in the karyotype are detected, the doctor explains to the patient the features of the detected pathology and talks about the nature of its impact on the life of the child. Particular attention is paid to incurable chromosomal and gene anomalies. The decision on the advisability of maintaining 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 can be made to prevent them in the future.

Karyotyping is the analysis of a set of chromosomes in a person. This study is carried out by examining blood lymphocytes, bone marrow cells, skin, amniotic fluid or placenta. Its implementation is shown at the stage of conception planning, but if necessary, the analysis can be carried out during pregnancy (on samples of cells from the parents or the fetus) or to an already born child. The results of karyotyping make it possible to detect the risk of developing chromosomal and genetic pathologies and to identify predisposition to certain diseases.

Genetic diagnostics occupies a special position in modern medicine. It allows you to clearly identify congenital malformations and predisposition to them. Karyotype analysis is one of the most popular methods of such diagnostics.

This concept was introduced by the Soviet scientist Grigory Levitsky at the beginning of the twentieth century. It includes the totality of all the features of a set of chromosomes inherent in the cells of a particular biological species, and in this case, the human body.

Normally, the human karyotype is determined by 46 chromosomes, organized into 23 pairs. In each pair, one of them is transmitted from the mother, and the other from the father.

More details in the video