Introduction. Chromosome abnormalities and microdeletions in the AZF (Yq11.2) locus of the Y chromosome are common genetic causes of male infertility caused by impaired spermatogenesis, however, the effect of their combined influence has not been sufficiently investigated. Aim: a comparative analysis of semen parameters in the Y-chromosome mosaics with and without AZF deletions. Methods. 16 male patients with Y chromosome mosaicism were examined. Chromosome analysis was done using by standard cytogenetic examination. Fluorescence in situ hybridization (FISH) was performed to identify/verify mosaicism and determine the structural Y chromosome abnormalities. The Y chromosome microdeletions were detected by multiplex PCR. The semen examination was carried out with the recommendations of the WHO Guidelines (2010). Results. Cytogenetically identifiable unbalanced the Y chromosome abnormalities were found in 13 patients (81.2%) of 16 patients. AZF deletion were detected in 8 patients (50%) of 16 patients. The patients were divided into two groups: group I - patients without AZF deletions (n=8), group II - patients with AZF deletions: AZFb+c, n=7 and AZFc (b2/b4), n=1 (n=8). Prominent difference in sperm diagnosis was revealed between the groups: in group I, there was a various degree of pathozoospermia (azoospermia - 3; oligoastenoteratozoospermia - 3; asthenoteratozoospermia - 2); in group II, only severe forms of pathozoospermia (azoospermia - 7; oligozoospermia severe - 1), as well as the frequency of oligospermia - 12.5% and 37.5%, respectively. A higher concentration of spermatozoa was found in patients without AZF deletions (group I - 15.9±31.0 million/ml, group II - 0.003±0.009 million/ml; p=0.026). There was no statistically significant difference between the average age of patients in the groups, ejaculate volume, pH and viscosity of ejaculate. Conclusion. There is high frequency of structural Y chromosome abnormalities and microdeletions in the AZF (Yq11.2) locus in the Y chromosome mosaics. Unbalanced cytogenetic Y chromosome rearrangements and pathogenic AZF microdeletions are characterized by a severe degree of spermatogenesis disorder in male patients with Y chromosome mosaicism. The preservation of fertility potential in men with Y chromosome mosaicism is possible in the absence of unbalanced rearrangements and severe types of AZF deletions.

Mining has a direct impact on the environment and on the health of miners and is considered one of the most hazardous occupations worldwide. The aim of this study was the analysis of chromosomal aberrations (CAs) in lung cancer patients and healthy donors resident in the same territory. Statistical analysis were performed using nonparametric statistics (Mann-Whitney U Test for paired comparison of quantitative characteristics), logistic regression. It was determined that the CAs frequency (both chromatid- and chromosome-type aberrations) was significantly increased in lung cancer patients compared to control group.

The microbiome of the respiratory tract can have a significant impact on the development of a number of diseases of the human respiratory system. In addition to dysbiotic changes in the composition of the microbiome of patients, it was noted that many bacteria have a genotoxic potential and are able to directly or indirectly damage the genome in the cells of the host organism. The aim of the study was to study the relationship between the composition of the sputum microbiome and the level of chromosome damage in the blood leukocytes of patients with lung cancer (LC). The taxonomic composition of the sputum bacterial microbiome, as well as the basic frequencies of chromosomal aberrations (CA) and micronuclei (MN) in blood lymphocytes of 66 men diagnosed with LC and 62 healthy donors were studied. The results of sequencing showed that the microbiome of LC patients has signs of dysbiosis with a significant increase in the content of bacteria of the genera Streptococcus, Bacillus, Gemella and Haemophilus. In patients with LC, a direct relationship was found between the frequency of aberrant metaphases in lymphocytes and the percentage of representatives of the genus Bacteroides in sputum.

Background. Non-invasive prenatal testing (NIPT) using whole-genome sequencing of DNA circulating in the pregnant woman blood is one of the most effective method for determining the risk of fetal chromosomal abnormalities without invasive interventions. This test, in addition to frequent abnormalities, allows to identify rare pathologies. However, the feasibility of whole-genome NIPT for detection of rare chromosomal abnormalities remains a subject of debate. Aim: to evaluate the effectiveness of whole-genome NIPT for the detection of rare fetus chromosomal abnormalities based on the D.O. Ott Research Institute of Obstetrics, Gynecology and Reproductology experience. Methods. In the period from December 2019 to May 2022, DNA samples isolated from the blood plasma of 4,600 women with singleton pregnancies were analyzed using whole genome sequencing technology. Results. In 182 (4.0%) cases, a high risk of fetal chromosomal abnormalities was found, of which 35 (19.2%) cases were rare pathologies. More common were trisomy on chromosome 16 (ten cases), on chromosome 19 (in three cases), less often - trisomy on chromosomes 8, 9, 20, 10, 22 (in two cases), on chromosomes 2, 3, 4, 5, 11, 12, 14, 15 (one case each), monosomy on chromosomes 21, 18 and 13 (one case each), one case of multiple aneuploidy. The invasive diagnostic results were obtained for 11 women, other patients refused invasive procedures. The identified rare anomalies were confirmed in 6 cases (54.5%).

The cytogenetic assay of bone marrow or peripheral blood cells in persons with lymphoproliferative diseases is mandatory and necessary. The results help a doctor with the diagnosis of the disease and the choice of treatment tactics as early as possible after the patient’s visit to the hematologist. Modern molecular cytogenetic approaches based on the use of locus-specific fluorescent probes (FISH method) make it possible to quickly and accurately obtain information about the presence or absence of the most common mutations. The aim of this work is to analyze our cytogenetic data given with a “cocktail” of 5 locus-specific fluorescent probes in individuals with lymphoproliferative diseases, most of whom were diagnosed with CLL. A cytogenetic study was conducted in 16 patients in the period 2014 - 2022 in the Laboratory of Radiation Genetics of the URCRM. A cocktail of locus-specific probes was used: ATM (11q22)/TP53 (17p13) and DLEU (13q14)/LAMP (13q34) and cen 12 (12p11.1;12q11.1). Seventy five percent of the examined individuals were carriers of mutations. The most common mutations were del17p13 (50%), del13q14 (50%). We believe that if a patient has a mutation in 13q14, it is necessary to conduct an additional study on del13q14.2 (RB1).

Introduction. Abnormal number or structure of chromosomes is known to be one of the reasons of birth defects. About 0.5% of newborns are known to display chromosomal diseases [1], which are as a rule, have severe manifestation. Clearly then, prenatal diagnostics (PD) of chromosomal anomalies is of vital importance. Here, we describe the advantages of the approach for cultivating the amniotic fluid (AF) cells, which has been developed in the cytogenetics lab of the CNMT, and summarize the results of karyotyping data spanning the period of 10 years. Aim: to perform PD of chromosomal pathologies using the classical cytogenetics methods, and to do so with the shortest turnaround time possible using high-resolution differential chromosome staining technique. Methods. Cord blood samples, chorionic/placental villi or AF. Ex vivo cell culture, metaphase chromosome spreads, differential chromosome staining using standard protocols. The stained chromosomes were analyzed under a light microscope and images were captured using a videocamera and processed with appropriate software. ISCN (2009) was used for chromosome descriptions. Results. Laboratory associates have developed and patented the approach to shorten the AF cell culturing time to 8-13 days. Over the period of 10 years, 228 cytogenetic studies were performed, and chromosomal pathologies were uncovered in 11.8% cases. PD performance constituted 100%. Of all the chromosomal pathologies identified, chromosome rearrangements were observed in 40.7% samples. Conclusions. Optimizing AF cell culture conditions has allowed to rapidly and comprehensively perform karyotyping of fetal cells. Laboratory performance in PD was very high.

Introduction. The search for biological markers of individual radiosensitivity remains an extremely urgent problem of modern medicine. Aim: to evaluate of the copy number aberrations in the blood lymphocytes of workers exposed to occupational radiation exposure. Methods. The object of the study was the blood of 20 relatively healthy workers of the Siberian Chemical Combine, exposed to external radiation. A standard cytogenetic analysis was performed for all the examined individuals. The blood DNA was examined using a «CytoScan HD Array» microarray («Affymetrix», USA). To process the results of microchipping, a program was used «Chromosome Analysis Suite 4.3» («Affymetrix», США). Results. For4 workers found out 4 CNA: 3 mosaic amplifications, 1 mosaic deletion. Conclusion. The detected 4 candidates for the origin of de novo CNA were not induced by chronic low-intensity radiation, as they did not show an association with radiation. In this study, the assumption about the connection of de novo CNA with the radiosensitivity of individuals was not confirmed. Further studies of the mechanisms of XA preservation are needed in order to detect markers of individual radiosensitivity.

Single-gene copy number variations (CNVs) in patients with impaired psychomotor development are detected with a frequency of up to 10%. The outcome of this type of aberration is more obvious if a dosage-sensitive gene associated with the disease is affected. However, a pathological phenotype can also be formed as a result of hemizygotization of a recessive nucleotide sequence variant from an intact homologue or by combining CNV and a nucleotide variant (compound heterozygote). We have developed and tested for 1176 patients an algorithm for the molecular diagnosis of hereditary pathology associated with single-gene CNV. Pathogenic, likely pathogenic and structural chromosomal aberrations with uncertain clinical significance were detected in 478 probands (40.6%), including monogenic CNV in 60 patients (5.1%). Among 32 single-gene aberrations, the presence of which was confirmed by real-time PCR, most were inherited from healthy parents (23 CNV or 72%). Seven patients underwent sequencing. Not a single pathogenic nucleotide sequence variant was identified on the intact homologue, but in some cases, previously unreported variants of uncertain significance were found in genes not involved in CNV.

The aim of the research was to study the influence of the chronic radiation exposure and non-radiation factors on the length of the telomere regions of the human chromosomes. The object of the study: peripheral blood T-cells of the chronically exposed residents of the Techa riverside settlements. The length of the telomere regions of the 1st, 2nd, 3rd, 13th, 14th, 15th,19th, 20th, 21st and 22nd pair of chromosomes has been estimated using the method of fluorescent staining (Q-FISH) of the telomeres coupled with DAPI counterstaining. The findings of the study demonstrate that the length of the telomeres in one cell varies greatly; the size of the telomere region does not depend on the length of a chromosome or a chromosome arm where it is located. The value of the telomere length in men is statistically significantly high as compared to women. In the comparison group, the length of the telomere regions in many chromosomes statistically significantly exceeds that in the exposed group.

We present the results of a molecular-genetic study of 4 patients with complex genomic rearrangements and «chromosomal phenotype», which may include phenotype anomalies, intellectual disabilities, and multiple congenital abnormalities. FISH analysis, CMA and Hi-C were carried out in patients with “apparently” balanced chromosomal rearrangements associated with an abnormal phenotype to identify and estimate the genomic imbalance. The identification of the structure, mechanisms of formation and genomic imbalance in these cases allows us to characterize complex genomic rearrangements and assess individual genetic risks in the family.

Molecular karyotyping of 1176 patients with neuropsychiatric development delay was performed and 53 patients with X-linked CNVs were identified. Based on the results, a diagnostic algorithm was developed and tested for patients carrying X-linked CNV. The algorithm involves the analysis of pathogenic significance of CNV using databases (DGV, OMIM and DECIPHER) and investigating the X-chromosome inactivation in CNV carriers. An integrated approach makes it possible to identify pathogenetically significant rearrangements on the X-chromosome in families and perform personalized genetic counseling for these families.

Background. Meiotic quadrivalent asymmetry degree or the presence of terminal breakpoints may affect the risk of unbalanced gametes’ formation due to pathological chromosome segregation in autosomal reciprocal translocations (ART) carriers during meiosis. A comprehensive analysis of these factors in preimplantation embryos allows evaluating the entire spectrum of segregation patterns in ART carriers for subsequent risk assessment. Aim: the purpose of the study was to assess the influence quadrivalent asymmetry degree and the presence of terminal breakpoints on the segregation type in ART carriers. Methods. Karyotyping for ART confirmation, preimplantation genetic testing (PGT-SP) using fluorescent in situ hybridization (FISH) on 271 embryos obtained in assisted reproductive technology (ART) cycles in 26 couples of ART carriers. The chromosome segregation patterns, the quadrivalents’ asymmetry degree, and the presence of terminal breakpoints were determined. Results. An alternative segregation type, leading to the formation of balanced gametes, was observed with the same frequency in ART carriers with and without terminal breakpoints, as well as in carriers with different quadrivalent asymmetry degrees. The 4:0 and 3:1 patterns were more common in ART carriers with severe quadrivalent asymmetry and terminal breakpoints and could result in large-scale chromosomal imbalance. The data obtained can be used in genetic counseling of ART carriers.

Ring chromosome 13 is a rare type of chromosome structural abnormalities. A change in the linear structure of the chromosome into a circular one causes its mitotic instability, leading to somatic dynamic mosaicism, which results in the formation of cell clones with various secondary numerical and structural chromosomal rearrangements. We report here a study on ring chromosome 13 instability in lymphocyte and fibroblast cultures established from a child with developmental delay, microcephaly and congenital abnormalities. The cytogenomic analysis revealed a different structure of secondary genomic imbalance, variable levels of dynamic mosaicism and selective karyotype evolution.

Wolf-Hirschhorn syndrome (WHS, OMIM 194190) is one of the most common microdeletion syndromes, represented by a heterozygous deletion of the short arm of chromosome 4 (4p16.3). The main clinical features of patients with WHS include: craniofacial features - “Greek warrior helmet”, prenatal and postnatal growth deficiency, developmental disability of variable degree, and seizures. To date, several mechanisms for the formation of 4p16.3 deletions and several critical regions responsible for phenotypic manifestations in patients have been described. In our study, we present five cases of 4p16.3 deletion with different origins and mechanisms of formation.

Relevance. Comparison of microRNA expression in lymphoma and normal lymphoid tissue revealed a decrease in the expression level of a number of p53-induced oncosuppressive molecules, such as miR-34a, miR-34b/c, miR-129 and miR-203, which, in addition to mutations in the TP53 gene, can be caused by aberrations in the genome regions encoding the microRNAs themselves. Purpose. To carry out a comprehensive analysis of the p53-responsive microRNAs genes MIR-34A, MIR-34B/C, MIR-203 and MIR-129-2 methylation and mutations of the TP53 gene in diffuse large B-cell lymphoma (DLBCL). Methods. 73 samples of DNA isolated from tumor tissue of patients with DLBCL were analyzed. The nucleotide sequence of the TP53 gene DNA-binding domain was determined by capillary direct Sanger sequencing. The methylation status was determined by methyl-specific PCR (for MIR-203 and MIR-129-2) and methyl-sensitive analysis of high-resolution melting curves (for MIR-34A and MIR-34B/C) using DNA treated with sodium bisulfite. Results. The frequency of MIR-34A, MIR-34B/C, MIR-203 and MIR-129-2 genes methylation and TP53 gene mutations was 27%, 62%, 66%, 67% and 25%, respectively. Methylation of the analyzed genes of p53-responsive microRNAs and mutations in the TP53 gene in the tumor tissue of DLBCL in the most patients tended to mutual exclusion. A significant association (p < 0.05) was shown between the methylation of the MIR-203, MIR-129-2 and MIR-34B/C genes, as well as the MIR-34B/C and MIR-34A pair. In 14% and 47% of DLBCL cases all four genes and three of the analyzed genes were methylated, respectively. Conclusions. Along with mutations in the TP53 gene aberrant methylation may be an independent cause of decreased miR-34a, miR-34b/c, miR-129 and miR-203 expression. Methylation of the MIR-34A, MIR-34B/C, MIR-203 and MIR-129-2 genes in the tumor tissue of DLBCL in most cases is of a combined nature.

Currently, the epigenomic landscape underlying hypertension and dyscirculatory encephalopathy is poorly understood. Identification of the epigenetic pattern in combination with genetic passport can provide additional information about the etiology of diseases and the risk of complications, as well as the choice of strategy and tactics of treatment. We carried out a quantitative assessment of the level of genome-wide DNA methylation and the degree of chromatin compaction in peripheral blood leukocytes in patients with hypertension and dyscirculatory encephalopathy, and also in healthy volunteers from St. Petersburg. Gender differences in the risk of developing dyscirculatory encephalopathy were revealed in patients with hypertension. It was found that the level of DNA methylation and the degree of chromatin compaction are increased in hypertension (compared to control). In the studied groups, men and women showed different epigenomic reactions of leukocytes to drug therapy in these pathologies.