Laboratory of molecular-genetic diagnostics

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Laboratory staff:

• Laboratory assistant doctor Ivanovicheva Natalia Sergeevna
• Paramedic-laboratory assistant  Nikitina Elena Alekseevna

The laboratory is engaged in DNA diagnostics of hereditary and infectious diseases. DNA diagnostics combines several research methods, the most common of them is the PCR (polymerase chain reaction) method. Polymerase chain reaction is a highly accurate method of molecular genetic diagnostics, which makes it possible to identify various diseases in humans, both in the acute and chronic stages, and long before the disease can manifest itself.

Infections detected by PCR diagnostics:

• viral hepatitis B, C;
• cytomegalovirus infection;
• papillomavirus infection (including its oncogenic types);
• herpes infection;
sexually transmitted infections (ureaplasmosis, gardnerellosis, chlamydia, mycoplasmosis, trichomoniasis).

The material for PCR diagnostics can be:

scraping of epithelial cells (scraping from the urethra in men and women, scraping from the cervical canal); blood, plasma, blood serum; biological fluids (prostate juice, pleural, spinal, amniotic, articular fluids, saliva); urine (the first portion of morning urine is used), etc.

Rules of preparation for the collection of biological material for carrying out

PCR diagnostics of infections.

To obtain reliable results, tests for the detection of pathogens of bacterial infections should be carried out at least 2 weeks after the last intake of antibiotics / antibacterial drugs.

• Blood should be given on an empty stomach or 5 hours after the last meal.
• Urine (the first portion) is collected in the morning, after a thorough toilet of the external genitalia.
• When taking biomaterial from the urogenital tract, it is recommended to refrain from urination and sexual intercourse for 2 hours before taking a sample. In women, the material is taken before menstruation or 1-2 days after its end.

It must be remembered that the results of studies for the presence of infections depend on the period of infection and the state of the immune system, so a negative result does not completely exclude the presence of infection. In doubtful cases, it is recommended to conduct a second study after 3-5 days.

Diagnosis of hereditary diseases.

Genetics of male infertility.

• Frequent deletions in the AZF locus of the Y chromosome (AZFa, AZFb and AZFc).

Approximately 5% of men of reproductive age have various deviations in quantitative or qualitative indicators of sperm. When oligozoospermia, azoospermia are detected, the genetic cause of infertility is present in 30-50% of cases. According to the letter of the Ministry of Health of the Russian Federation dated April 11, 2003 No.2510/3797-03-32 genetic diagnostics is recommended to identify genetic factors of male infertility. The most frequent genetic factor is Y-chromosome deletions in the AZF region (azoospermia factor). In men with deletions of the AZF locus, there is a probability of progression of disorders of spermatogenesis with age (from oligozoospermia to azoospermia). Deletions of the AZF locus will be transmitted to all born boys, so future parents need to know that their sons will have the same problems as their fathers.

The AZF locus is divided into 3 sections: AZFa, AZFb and AZFc. In each of them, genes involved in the control of spermatogenesis have been identified. Deletions in the AZF locus can be complete, i.e. completely removing one of the AZF regions or more, and partial when they do not completely capture any of its three regions.

With complete AZF deletions, there is a fairly clear dependence of the degree of violation of spermatogenesis on the size and localization of deletions, which may have a prognostic value in obtaining spermatozoa suitable for in vitro fertilization programs.

• The most frequent mutations in the CFTR cystic fibrosis gene (F508del, G542X, W1282X, N1303K, 2143delT, 2184insA, 3849+10kbC>T, dele2.3(21kb).

Predisposition to habitual miscarriage of pregnancy in the early stages.

• Analysis of polymorphisms in folate cycle genes (MTHFR, MTR, MTRR)
• Analysis of polymorphisms in the genes of coagulation system factors (F2, F5, F7, F13A1, FGB, ITGA2, ITGA3, PAL-1)/
• Typing of a married couple by three histocompatibility genes of HLA class II (DQ A1, DQ B1, DR B1).

Predisposition to isolated fetal malformations.

• Analysis of polymorphisms in folate cycle genes (MTHFR, MTR, MTRR)

Typing of histocompatibility genes (HLA) of class II

HLA (human leucocyte antigens, human leukocyte antigens) class II genes include 24 genes whose protein products belong to the main histocompatibility complex. They play an important role in the regulation of recognition of foreign agents and are necessary participants in many immunological reactions. Of all the HLA class II genes, 3 genes are of the greatest importance: DQA1, DQB1, DRB1.

Typing of HLA class II genes is used to diagnose infertility and miscarriage. For HLA typing, both spouses must donate blood from a vein (on an empty stomach or 5 hours after eating). Blood can be donated in the MGK treatment room from 8.00 to 15.00 . Leukocytes are isolated from venous blood. On their surface there are protein molecules – antigens of the main histocompatibility complex (HLA antigens). Each person's set of antigens is unique. A complete mismatch of HLA genotypes in spouses is favorable for the development of pregnancy. If the results of the examination revealed coincidences that the doctor considered a threat to conception and pregnancy, he will prescribe appropriate treatment to the couple.

Thrombophilia

Thrombophilia is a change in the balance of the blood coagulation system, manifested by an increased tendency to the process of thrombosis. Thrombophilia is characterized by a long course and sudden manifestation of complications (phlebothrombosis, thromboembolism).

Any person may have signs of thrombophilia, but the degree of their manifestation will vary depending on the presence of a combination of risk factors for this pathology.

All thrombophilia are divided into two main groups: hereditary and acquired.

Acquired factors rarely become the root cause of thrombophilia

Hereditary or congenital thrombophilia is caused by a mutation of one or both copies of genes encoding factors of the coagulation or anticoagulation systems.

Hereditary risk factors for the development of thrombophilia include: lack of antithrombin III, deficiency of prothrombin S and C, mutation of factor V and prothrombin genes, dysfibrinogenemia, elevated blood lipoprotein levels, sickle cell anemia and thalassemia.