Karyotyping of peripheral blood lymphocytes of a spouse. How and why karyotyping is performed for expectant mothers and fathers - examination mechanism

The karyotype reflects the chromosome composition of a person. Normally, a person has 46 chromosomes or 23 pairs. 23rd pair - sex chromosomes - XX in women, XY in men. Karyotype analysis held for children and adults. The child's karyotype allows us to exclude some genetic diseases. Karyotyping of spouses helps to identify the genetic cause of infertility and miscarriage, as well as the prognosis of healthy offspring.

What is a karyotype?

Karyotype- a complete set of chromosomes in human cells. The normal chromosome content in human somatic (non-embryonic) cells is 46 chromosomes, organized into 23 pairs. Each pair consists of one chromosome received from the mother and one received from the father. To study a person's karyotype, blood is taken from a vein. In the CIR Laboratory, karyotyping is carried out using cytogenetic and molecular genetic methods. There is also FISH karyotype analysis, which allows you to analyze chromosomes using fluorescent dyes.

The CIR laboratory conducts the following karyotyping tests:

The first three analyzes are performed using the cytogenetic method. CMA is a molecular genetic analysis of a karyotype.

Let's talk about the cytogenetic method of performing karyotype analysis.
The appearance of chromosomes changes significantly during the cell cycle: during interphase, chromosomes are localized in the nucleus, as a rule, despiralized and difficult to observe, therefore, to determine the karyotype, cells are used in one of the stages of their division - metaphase of mitosis. Chromosomes in a light microscope at the metaphase stage are DNA molecules packaged with the help of special proteins into dense supercoiled rod-shaped structures. Thus, a large number of chromosomes are packed into a small volume and placed in a relatively small volume of the cell nucleus. The arrangement of chromosomes, visible in a microscope, is photographed and from several photographs a systematic karyotype is collected - a numbered set of chromosomal pairs of homologous chromosomes. In this case, the chromosome images are oriented vertically, with short arms up, and their numbering is carried out in descending order of size. A pair of sex chromosomes (X and Y in a man, X and X in a woman) is placed at the very end of the image of the chromosome set.

When is blood donated for karyotype?

Karyotype examination is a non-routine analysis, for which there are indications.

Reasons why a doctor may suggest an examination may include:

the birth of a child with a genetic pathology or the presence of a chromosomal pathology in relatives of one of the spouses;
infertility in the family;
recurrent miscarriage and/or spontaneous miscarriage in the first 12 weeks of pregnancy;
exposure to radiation, hazardous work at work, etc.

Which karyotype test should I take?

Karyotype analysis can be performed in two versions: karyotyping without aberrations and karyotyping with aberrations. The first analysis shows a person's genetic makeup - the number of chromosomes and major changes in all chromosomes received from the parents. Karyotyping with aberrations shows changes that occur in chromosomes during a person’s life under the influence of various harmful environmental factors. Karyotype analysis using the CMA method is performed in rare cases in case of growth retardation in children, autism, or suspected microdeletion syndromes.

Analysis for the karyotype of a married couple (karyotyping of spouses)

To identify the possible cause of infertility in the family, the doctor may prescribe karyotyping for spouses. Spouses can take the test at different times, this does not affect the interpretation. If there is an assumption about the genetic nature of infertility, a karyotype test can be assigned to one of the spouses. .

How to get tested for karyotype? Where can I get a karyotype test?

Karyotype: price of analysis

Find out the price of karyotype analysis in our price list.

Karyotype analysis: how is a human karyotype studied?

Each chromosome consists of specialized structures - a centromere and two telomeres. The centromere (cen) or primary junction divides the chromosome into two parts - the long (q) and short (p) arms and is responsible for the separation of chromosomes during cell division. Before cell division begins, a chromosome consists of one chromatid. After doubling the DNA - from two chromatids, until they are divided into two new cells.

For the karyotype determination procedure cytogenetic method any population of dividing cells can be used. To determine the human karyotype, peripheral blood lymphocytes are usually used. To analyze the karyotype, blood is taken from a vein into a sterile tube. There are no conditions for taking the test; you can have breakfast before visiting the laboratory.

The transition of lymphocytes from the resting stage G0 to proliferation is provoked by the addition of a cell division stimulator - phytohemagglutinin. Bone marrow cells or a primary culture of skin fibroblasts can also be used to determine the karyotype. To increase the number of cells at the metaphase stage, colchicine or nocadazole is added to the cell culture shortly before fixation, which block the formation of microtubules, thereby preventing the divergence of chromatids to the poles of cell division and the completion of mitosis.

After fixation, preparations of metaphase chromosomes are stained and examined under a microscope.

To obtain a classic karyotype, chromosomes are stained with various dyes or their mixtures: due to differences in the binding of the dye to different parts of the chromosomes, staining occurs unevenly and a characteristic banded structure is formed (a complex of transverse marks, English banding), reflecting the linear heterogeneity of the chromosome and specific for homologous pairs chromosomes and their sections (with the exception of polymorphic regions, various allelic variants of genes are localized). The first chromosome staining method to produce such highly detailed images was developed by the Swedish cytologist Kaspersson (Q-staining). \\Other dyes are also used; such techniques are collectively called differential chromosome staining.

Types of differential chromosome staining

G-staining- modified Romanovsky-Giemsa staining. The sensitivity is higher than that of Q-staining, therefore it is used as a standard method for cytogenetic analysis. Used to detect small aberrations and marker chromosomes (segmented differently than normal homologous chromosomes).

Q-staining- Kaspersson staining with quinine mustard with examination under a fluorescent microscope. Most often used to study Y chromosomes (quick determination of genetic sex, detection of translocations between the X and Y chromosomes or between the Y chromosome and autosomes, screening for mosaicism involving Y chromosomes).

R-staining- acridine orange and similar dyes are used, and areas of chromosomes that are insensitive to G-staining are stained. Used to identify details of homologous G- or Q-negative regions of sister chromatids or homologous chromosomes.

C-staining- used to analyze centromeric regions of chromosomes containing constitutive heterochromatin and the variable distal part of the Y chromosome.

T-staining- used to analyze telomeric regions of chromosomes.

Chromosomal microarray analysis (CMA)

More modern technology for karyotype research. Karyotype analysis is performed using the molecular genetic method aCGH (microarray comparative genomic hybridization), which, unlike the classical cytogenetic method, has a high resolution ability to detect smaller structural changes in the karyotype.

Fluorescent in situ hybridization, English. Fluorescence in situ hybridization, FISH

Detection of aneuploidy - a violation of the number of chromosomes. In the image, the green color corresponds to chromosome 13, and the red color corresponds to 21, which indicates the presence of triploidy on chromosome 21 in this sample.

Recently, the so-called spectral karyotyping technique (fluorescence in situ hybridization, FISH) has been used, which consists of staining chromosomes with a set of fluorescent dyes that bind to specific regions of the chromosomes. As a result of such staining, homologous pairs of chromosomes acquire identical spectral characteristics, which not only greatly facilitates the identification of such pairs, but also facilitates the detection of interchromosomal translocations, that is, movements of sections between chromosomes - translocated sections have a spectrum that differs from the spectrum of the rest of the chromosome.

Disturbances in the structure of chromosomes may not manifest themselves during life. But when the fusion of an egg and a sperm occurs, two genetic sets meet, and then an unsuccessful match of genes can cause a miscarriage or the formation of a congenital pathology in the fetus. Karyotyping of spouses helps to identify abnormalities in the structure and number of chromosomes, as well as the likelihood of a particular abnormality.

Karyotype examination is an optional analysis. The procedure has its own indications, including a history of miscarriages and frozen pregnancies. Reproductive problems associated with genetic characteristics are quite rare.

Karyotyping is a diagnostic procedure that identifies abnormalities in the structure and number of chromosomes. Such deviations can cause hereditary pathologies in the child and infertility of the spouses.

Each person has his own specific set of genes, which is called a karyotype. Chromosomes are arranged in pairs: 22 pairs of autosomes and 1 pair of sex chromosomes, which are represented as XX in the female body, and XY in the male body. They consist of genes - areas that are responsible for the manifestation of a particular trait.

Karyotyping detects diseases directly related to changes in DNA. The defect may be in a gene, in the structure of chromosomes or in their number. The most famous example is Down syndrome, also called trisomy 21.

Karyotyping of spouses (cytogenetic analysis) is a study of blood cell chromosomes. The procedure identifies the causes of miscarriage or infertility in couples when other factors have already been excluded (hormonal, immune, infectious). If increased genomic instability is detected, the use of antioxidants and immunomodulators will help reduce the risk of failures during conception.

Which couples are recommended for karyotyping?

As already noted, karyotyping of spouses is not included in the list of mandatory diagnostic procedures. It is indicated in the following cases:

One or both parents are over 35 years of age.
Infertility, the causes of which cannot be determined by other methods.
Several unsuccessful IVF procedures.
Living in areas with poor environmental conditions, working in hazardous industries, contact with hazardous chemicals.
Smoking, alcohol abuse, taking drugs, certain medications.
Previous miscarriages, missed pregnancies, premature births.
Spouses are blood relatives.
Previously born children with genetic diseases.

Preparing for the examination procedure

The analysis is carried out in a laboratory and does not pose any danger to the health of the spouses. 2 weeks before the procedure you need to stop drinking alcohol, tobacco products and medications. If taking any medications cannot be stopped, you need to warn the laboratory technician about this.

Blood is drawn on a full stomach; the last meal should occur 1-2 hours before the test. Before the procedure itself, you need to fill out a special questionnaire or bring it with you (in some cases it is filled out by the doctor in advance). If karyotyping of spouses coincides with an exacerbation or acute course of an infectious disease in one or both of the couple, then the study must be rescheduled.

Carrying out analysis

During karyotyping, blood is drawn from a vein. The laboratory assistant fills the test tube with it and releases the patient. Genetic analysis and preparation of results usually takes about 5 days.

For further research, only part of the material will be needed - lymphocytes. They are isolated from the blood during the division period. In order to provoke the activity of this process, special drugs are added (Colchicine, Nocazadol). Over the next three days, the features of cell reproduction are analyzed. Based on the results obtained, a conclusion is drawn about possible pathologies and risks of miscarriage.

Modern technologies make it possible to perform karyotyping using only 15 cells and special preparations. Therefore, one blood draw is enough to obtain accurate and complete information about chromosomes and genes.

What will the result be?

The interpretation of the karyotyping analysis of spouses is carried out by a geneticist. The normal result for women is 46ХХ, for men – 46ХУ. It means that a total of 46 chromosomes have been discovered, the last pair of which is the sex chromosome. When a genetic pathology is detected, this formula changes. For example, with Down syndrome (trisomy 21), it looks like 46XX21+.

The result of karyotyping helps to identify the following pathologies:

Trisomy is the presence of an extra third chromosome in a pair. Trisomy on the 21st chromosome - Down syndrome, on the 16th - spontaneous miscarriage in the 1st trimester, on the 13th - Patau syndrome, on the 18th - Edwards syndrome. Of these, the only viable option is Down syndrome.
Monosomy is the absence of one chromosome from a pair. Monosomy of any autosomal chromosome leads to early embryonic death. A similar pathology in a pair of XX in women is manifested by Shereshevsky-Turner syndrome.
Deletion is the absence of part of a chromosome. If large areas are lost, early embryonic death occurs. In other cases, genetic pathologies may develop (for example, cry-the-cat syndrome due to deletion on chromosome 5) or a positive effect on vitality (for example, resistance to HIV). Deletion of the sex chromosome in men causes disturbances in spermatogenesis and leads to infertility.
Duplication is the presence of a double fragment of a chromosome. The functions of the original genes are not affected.
Inversion is a turn of any part of a chromosome by 180°. Some of these changes are normal, others lead to the death of germ cells and the formation of unbalanced material in them. The result is decreased fertility, increased risk of miscarriage and fetal abnormalities.
Translocation is the movement of a section of a chromosome. Some of these changes do not affect the person in any way, others lead to miscarriages and congenital anomalies of the fetus (Robertsonian translocations).

The results form records changes in chromosome structure. The long arm is designated by the letter “q”, the short arm by “t”. For example, cry-the-cat syndrome (deletion on chromosome 5) is written as 46ХХ5t or 46ХY5t.

The second thing that is detected by karyotyping is changes in genes. Can be identified:

Gene mutations affecting blood clotting. Increased thrombus formation can cause miscarriage, infertility, or failure of fertilized egg implantation.
Gene mutations on the Y chromosome are the cause of male infertility, requiring the use of donor sperm.
Gene mutations that reduce the body's ability to detoxify - get rid of harmful substances received from the external environment.
Changes in the cystic fibrosis gene that lead to the development of this disease in a child.

Deviations from the norm have been identified: what to do?

To obtain complete information about the results of karyotyping, spouses need to come for a consultation with a geneticist. He will tell you in detail about the possible risks and likelihood of developing a particular disorder.

Karyotyping is one of the new methods of cytogenetic research, through which sets of human chromosomes are studied (the so-called karyotype). Scientists, conducting their studies, can determine the structure of chromosomes and, if this occurs, a violation in their structure. It is enough to carry out karyotyping of chromosomes once in a lifetime - the results of the study determine the genome of the male and female individuals for consistency with each other. In other words, thanks to such analyzes it is possible to check whether a man and a woman match at the genetic level, whether they can have children and whether their baby will be healthy.

The karyotyping method is the latest medical proposal, which, however, is becoming more and more popular every year among young (and not so young) spouses.

A karyotype is a complete set of chromosomes, with a description of certain characteristics - be it size, shape, number. In humans, as is known from the course of elementary biology, there are 46 chromosomes in the genome - a total of 23 pairs. Moreover, 44 chromosomes are autosomal: they are responsible for transmitting data that indicate hereditary traits of one kind or another. This includes hair color and type, ear structure, quality of vision, etc. But one pair of chromosomes is responsible for sexual characteristics - it is the one that gives the female karyotype (“XX”) or male (“XY”).

Thanks to the decoding of chromosomes, their comparison and connection, scientists can say with 99% accuracy what the probability of having a defective or sick baby is.

Molecular karyotyping: indications

Of course, it would be absolutely correct if absolutely all parents undergo karyotyping before having children. Moreover, regardless of whether doctors prescribe such an analysis or not. Perhaps in the future such analyzes will be mandatory, but not today. For now, people are referred for karyotyping only if there are compelling reasons for this.

A number of hereditary diseases that occurred in a particular person’s family sometimes appear quite unexpectedly (albeit predictably). Several generations can be absolutely healthy, and then some kind of disease suddenly appears. It is karyotyping that can identify the same pathology in the unborn child and calculate all the risks in advance.

An analysis is required if:

One or both spouses who decide to have a child are over 35 years old.
A woman cannot get pregnant for a long time, and doctors cannot determine the origin of infertility.
There were repeated attempts to carry out artificial insemination, but all of them were unsuccessful.
One of the spouses had some hereditary diseases in their family.
The woman has some kind of disorder, an imbalance of hormones in the body.
The man has a history of impaired spermatogenesis, and the cause of the impaired sperm formation has not been established.
One of the spouses came into contact with hazardous chemicals.
One of the spouses received radiation exposure.
The couple live in an unfavorable environmental environment.
There were moments in the past that could negatively affect the child. For example, the woman or man previously smoked, drank alcohol or drugs, or took a lot of medications.
A woman had three or more pregnancies terminated spontaneously (miscarriage, frozen pregnancy, premature birth).
A man and a woman are closely related.
The couple already has a child with some kind of congenital pathology and developmental defect.

It is best to undergo karyotyping when planning a pregnancy. But now it is possible to study the karyotype of the baby that a woman is carrying - so-called prenatal karyotyping is carried out.

Karyotyping: preparation for analysis

To determine the karyotype, blood cells are needed. In order for the analysis to be more accurate and of high quality, everything possible must be done to eliminate factors that complicate cell growth. That is why preparation for karyotyping often takes two or more weeks.

If you decide to check your karyotype, you need at least 14 days:

No smoking.
Do not drink alcoholic beverages.
Do not take medications (this primarily applies to antibiotics).
Do not get sick (this applies to both infectious colds and exacerbations of various chronic diseases).

Karyotyping: how to take it

To identify a person’s karyotype, venous blood is required, which is taken from a man and a woman (it is very important that both spouses are ready for testing).
Having received venous blood, the laboratory sifts out lymphocytes (they are just in a state of division (mitosis phase)).
To conduct a qualitative analysis, 12 to 15 lymphocytes are sufficient - this is enough to identify quantitative and qualitative chromosome discrepancies - they are the ones that indicate the presence of any genetic hereditary diseases.
Lymphocyte cells are monitored for three days - their division, growth and reproduction are analyzed.
To stimulate the mitosis phase, lymphocyte cells are treated with a special compound - mitogen.
When the immediate process of division occurs, scientists study the chromosomes - in this case, mitosis must be stopped using a special treatment.
Once scientists have collected enough data, they prepare special preparations to examine chromosomes on glass.
To make the structure of the chromosomes clearer, it is possible to add paint, which allows the genome to acquire color. Since chromosomes have individuality, after coloring they can become even more noticeable.
At the final stage, the stained smears are subjected to analysis, which can determine not only the total number of chromosomes, but also the separate structure of each.
By comparing paired chromosomes and their striations, scientists check the results obtained with their table, which describes the norms of cytogenetic patterns of chromosomes.

Karyotyping: results

An analysis to study the karyotype must be taken in a specialized clinic by a geneticist. If you are offered to undergo tests in a regular hospital, then there is a risk that the analysis will be unreliable, since most often in regular medical institutions there are no qualified doctors and equipment to perform the process itself.

If the analysis corresponds to the norm, then it should look like “46XX” (female) or “46XY” (male). In the event that specialists suddenly discover a genetic disorder, the recording will be more complex. For example, “46XY21+” means that a man has a pathology in the form of an extra chromosome (moreover, 21 means that the third chromosome is present in 21 pairs).

Thanks to karyotyping, it is possible to identify pathologies such as:

trisomy - the presence of a third extra chromosome in a pair (Down syndrome is likely);
monosomy - the absence of one chromosome in a pair;
deletion – loss of some part of a chromosome;
duplication – doubling of one of the fragments of a chromosome;
inversion - incorrect rotation of some part of the chromosome;
translocation - castling of certain sections of a chromosome.

If a deletion is found on the Y chromosome, this most likely indicates a violation of spermatogenesis and, as a consequence, infertility in a man. In addition, it is the deletion that most often causes congenital pathology in a child.

To make it convenient, if there are any irregularities in the structure of chromosomes, scientists write down test results using Latin letters. For example: the long arm is designated “q”, the short arm is designated “t”. If a woman has a history of loss of a fragment, say, the short arm of the fifth chromosome, then the entry will be “46ХХ5t”. This genetic deviation is called “cat cry” - the baby born to such a couple will most likely have congenital disorders, he will also cry for no reason.

Thanks to karyotyping, it is possible to assess the state of genes, as it is possible to identify:

A gene mutation that affects blood clot formation - this significantly impairs blood flow and can cause miscarriage or even infertility.
Gene mutation of the Y chromosome - pregnancy is possible, but only if there is another sperm (use of a donor).
Mutation of genes that are responsible for detoxification - this indicates that the body has a low ability to disinfect toxic factors.
A gene mutation that results in cystic fibrosis, which will help eliminate the risk of developing this disease altogether.

Modern equipment also makes it possible to identify a predisposition to diseases that do not have such a clear genetic characteristic: heart attack or diabetes mellitus, hypertension or joint pathology, etc.

Karyotyping: what to do next

If any abnormalities were detected during karyotyping, the doctor will immediately inform the spouses about this. It doesn’t matter whether it’s a gene mutation or a chromosomal aberration, in one or both spouses at once, a geneticist will explain everything in detail and clarify what the risks are for the unborn baby, how likely it is to have a sick child.
It is worth immediately noting that genetic pathology is incurable, if there are chromosomal disorders, then the spouses must make a very important and responsible decision: still give birth to their child (at their own peril and risk), use donor sperm (egg), attract a surrogate mother, not to give birth to a child, but to adopt a baby.
If doctors have identified chromosomal abnormalities in a woman during pregnancy, doctors explain that there is a possibility of having a sick child and advise terminating the pregnancy. But it is up to the future parents to decide whether to have an abortion or not. No one has the right to insist on termination of pregnancy - neither a doctor, nor a geneticist, nor any of the relatives.
If a chromosomal abnormality is in question or its presence results in a low percentage of the birth of a sick baby, then doctors prescribe a course of vitamins that reduce the likelihood of the baby being born with pathologies or abnormalities.

Fetal karyotyping: what is it?

If parents, for a number of reasons, did not carry out karyotyping during pregnancy planning and a new life is already ripening under the woman’s heart, then perinatal karyotyping can be performed. This method will help to identify the presence of chromosomal pathologies in the fetus already in the first trimester of pregnancy. This study will identify any abnormalities and guide doctors for treatment, adjustment or other unpopular actions necessary during pregnancy.

Thanks to this method, it is possible to exclude Down, Patau, Turner, Edwards and Klinefelter syndrome, as well as polysomy of the X chromosome.

Fetal karyotyping: methods

Currently, there are two methods that are used to conduct fetal examination.

Non-invasive method. Completely safe for both mother and baby. For this study, it is enough to conduct an ultrasound examination, which will take measurements of the fetus, as well as study the biochemical analysis of the pregnant woman to identify special markers.
Invasive method. A more serious method, since to identify pathology, manipulations must be carried out directly in the uterus. The doctor takes either cells from the chorion or cells from the placenta, as well as umbilical cord blood and a sample of amniotic fluid for analysis. This analysis is more accurate. Thanks to a biopsy of the above materials, doctors can obtain enough information about the baby’s health. The whole procedure is performed exactly as described above - a person’s karyotype is determined by studying the chromosome set.

Fetal karyotyping: complications

Before practicing the invasive method of fetal karyotyping, the doctor must inform that there is a small (no more than 2-3%) risk of complications after the studies. In the worst case scenario, a miscarriage is possible, bleeding may occur, or amniotic fluid may begin to leak.

That is why, before deciding on this procedure, you need to weigh all the pros and cons and only then give your consent. If you just want to find out the sex of the child at an early stage (and with this method this is quite possible), it is better to refuse invasive fetal karyotyping. It’s a completely different question if there is a risk of having a child with a genetic disorder or anomaly.

Fetal karyotyping: indications

Intervention during pregnancy to perform invasive karyotyping of the fetus is practiced only for medical reasons. This procedure is recommended if:

She is over 35 years pregnant and this is her first child.
An ultrasound examination showed the presence of pathology in the fetus.
In the blood of a pregnant woman, biochemical parameters - blood markers (AFP, hCG, PPAP) sharply changed.
There is a disease in the family that is transmitted only by gender (for example, hemophilia - this disease will be transmitted from a woman to her son, and not to her daughter).
The family already has a child with a pathology or developmental defect, or with a genetic disease.
Women experience miscarriages over long periods of time, as the fetus develops a developmental anomaly incompatible with life.
The child’s parents were exposed to radiation or worked for a long time (work) in hazardous work.
A pregnant woman suffered from a viral disease in the first trimester.
One or both parents used drugs.

What is karyotyping. Video

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. The 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 of congenital pathologies that can be inherited.

Sequence of karyotyping:

Collection of venous blood and screening of mononuclear leukocytes in the laboratory.
Placement of biological material in a medium with PHA (phytohemagglutinin) and the beginning of cell cultivation (mitotic division).
Termination of mitosis after reaching the metaphase stage, which is carried out with the help of colchicine.
Treatment with a hypotonic solution and production of microslides.
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 the total number of chromosomes, and any existing violations of the genetic code are recorded.

A genetic study is prescribed to assess the reproductive functions of a couple 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 with 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 the 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 recent 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:

Avoid alcohol, smoking and harmful foods.
Discuss stopping drug therapy with your doctor.
9-11 hours before collecting biological material, avoid eating.
Do not drink liquid 2-3 hours before the laboratory test.

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). If the biological material is of poor quality, difficulties may arise in 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:

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.
SKY (spectral)– a new technique that is considered to be the most effective, since it allows for visual and quick identification of violations. In this case, parts of chromosomes are detected using fluorescent tags without culturing cells. Used when standard karyotyping has failed.
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:

47XX+21 or 47XY+21 – Down syndrome (presence of an extra chromosome).
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 reveals dangerous abnormalities 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 the possible risks. There is no need to panic when chromosomal mutations are detected. 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 indicates possible consequences and gives recommendations if interruption is necessary.

Conclusion

Genetics currently represents a highly developed scientific field. With the help of modern diagnostic tests, it is possible to identify occurring deviations in the initial forms of 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.

Developmental deviations and difficulties conceiving a child are often associated with inherited disorders. If one of the parents has relatives suffering from genetic diseases, or he himself is a carrier, it is advisable to undergo testing before planning the birth of a baby. Doctors take a karyotype test if they suspect pathologies of chromosomes or DNA molecules. To conduct the study, blood is taken from the patient and treated with a staining compound. After processing, the size, shape and number of chromosomes are examined under a microscope.

Definition

A karyotype is an individual set of chromosomes, which has its own characteristics for each specific biological species and individual. A person has only 23 pairs of chromosomes, that is, a total of 46. Of the twenty-three pairs, only one determines sex, and the rest have no differences in structure. Genetic karyotype analysis allows you to identify abnormalities in the composition or structure of chromosomes. Thanks to this study, doctors can take timely measures to prevent the pathology from causing serious complications, including the death of the fetus.

Important! It is enough for future parents to undergo karyotyping once in their life to ensure the absence or presence of pathologies.

When to take a test

The analysis is relevant for people of any age, because not everyone has been examined by a geneticist since early childhood. There are no contraindications for pregnant and nursing mothers. But first of all, research is required for newborns, for whom early diagnosis will help identify dangerous genetic diseases that affect life expectancy. In-hospital analysis for the karyotype of spouses is often carried out as prescribed by a doctor, but not everyone knows what kind of examination this is. For couples wishing to have a child, examination is indicated in the following cases:

After repeated unsuccessful attempts to conceive.
Menstrual irregularities.
If there have been previous miscarriages or stillbirths.
In previously born children, delays in mental or physical development were recorded.
Already at the stage of pregnancy, developmental disorders were detected in the fetus.
If the future mother and father are close relatives.
If one of the parents has bad habits.
Living in a region with an unfavorable environmental situation or working in a hazardous industry.
Planning your first pregnancy after 35 years - the reason lies in the fact that chromosomes can change with age.
If parents have genetic diseases, even if healthy children were born before.

Attention! Modern doctors advise all couples to get tested, since not every carrier exhibits pathologies, and therefore many are not aware of them.

Problems, including infertility, are identified when a person decides to have a child.

How the research is carried out

The analysis is taken during the metaphase period, which lasts from two to ten minutes. It is at this moment that it is easiest to examine the chromosomes through a microscope. There are three ways to detect abnormalities - molecular, cytogenetic and molecular targeted. It is up to the doctor to select one method or another. Before the karyotype analysis is carried out, you need to prepare:

To cure colds, if a person is sick, then you can get tested no earlier than two weeks after recovery.
30 days before visiting the hospital, stop taking antibiotics or reduce their consumption according to the doctor’s instructions.
Do not drink alcohol for three days before testing.
On the day of the test, you should have a hearty breakfast.

Venous blood is taken for testing. The material obtained from the patient is treated with a dye to identify chromosomes. Next, the doctor takes several pictures, which make it possible to determine the number of DNA molecules and pathological changes.

Important. The molecular method is necessary to detect small areas of structural abnormalities of chromosomes less than 5 million nucleotides in size.

For more detailed diagnostics, an advanced or targeted molecular method is used.

How to decrypt

For representatives of the stronger sex, the normal karyotype analysis results are 46, XY, and for women - 46, XX. The number 46 indicates the normal number of chromosomes, and the X and Y at the end indicate the shape, structure and size of a healthy person - these indicators differ for men and women. Based on the test results, the doctor will make several notes on the form. Their decoding will help you understand medical terms:

Translocation - a chromosome rearrangement has occurred. If the patient has a balanced translocation, then it most likely will not manifest itself. If unbalanced, serious deviations are possible.
Mosaicism - cells with genetic characteristics different from normal are found.
Trisomy - this pathology occurs most often; the patient has an extra chromosome. The most common occurrence is the appearance of a copy of chromosome 21, leading to diseases such as Down syndrome.
Inversion - a section of a chromosome is rotated 180 degrees.
Monosomy is only one of the pairs of homologous chromosomes in a genotype.
Deletion – a fragment of a chromosome is lost.

What to do if deviations are found

You should not assume that anomalies in carinotype analysis always indicate that a married couple will have a sick child, or that they will be childless altogether. For example, parents with a balanced translocation may give birth to a healthy baby who will not have chromosomal pathologies. Even though the prices for karyotype analysis are high and start at three thousand rubles, it is not advisable to refuse it. Perhaps, based on the results, the doctor will advise you to undergo treatment and only then plan a pregnancy.

Attention! If a woman knows that she will have a child with pathologies, she needs to pay attention to a healthy lifestyle and follow the doctor’s recommendations.

Genetic abnormalities can occur in different ways. With trisomy of the thirteenth and eighteenth chromosomes, children die in the first year of life. People with Down syndrome have mental retardation, but the mortality rate is much lower than with similar diseases. Abnormalities of sex chromosomes, such as Shereshevsky-Turner syndrome, often lead to infertility, but a person with these disorders can live to old age. And with monosomy X, about 5% of women have the opportunity to give birth to a baby. It is important to consult a geneticist who will accurately diagnose. A genetic disease cannot be completely cured, but if you undergo regular treatment, your quality of life will improve.