Since the opening of the CRISPR / Cas genome editing system, this technology has made significant progress thanks to numerous modifications and improvements, coming close to application in clinical medicine. At present, the issue on its use for the treatment of genetic diseases, where the gene causing the disease is known, is on the agenda. With the help of this system, it is supposed to correct the mutant gene in cells taken from the patients themselves with the subsequent introduction of these cells back to the patient, or to correct in situ the mutation directly on the spot in the target gene in patients.

Introduction. Plasma circulating cytokines FGF-21 and GDF-15 are recently described and actively investigated cell’s metabolism regulators. They both have endocrine function and highly expressed in liver upon stress and starvation. Several studies established these markers as highly sensitive and specific for diagnosis of patients with mitochondrial diseases, especially those with prominent muscle system involvement. Mitochondrial diseases are clinically and genetically heterogeneous group of diseases. Aim. In our study we aimed to reveal the role of this markers in differential diagnostic of mitochondrial diseases. We measured plasma FGF-21 and GDF-15 concentration in 107 patients with genetically confirmed primary mitochondrial disease and control group. Results. The concentration of FGF-21 and GDF-15 in the group of patients with mitochondrial diseases was significantly higher than in the control. GDF-15 showed higher sensitivity and specificity (0.89, 0.88, AUC = 0.932) than FGF-21 (0.75, 0.69, AUC = 0.82). Especially sharp increase of both markers (100-200 times) was noted in the group of mitochondrial hepatopathies, GDF-15 showed the ability to distinguish some other forms of mitochondrial disease among themselves.

Background. The use of high-throughput parallel sequencing (NGS) is fraught with errors: not all of the genetic variants that are detected by NGS are true and are confirmed by alternative methods. Incorrectly mapped reads contribute to the appearance of false-positive variants. We believe that for targeted sequencing using Ion AmpliSeq technology, the task of excluding erroneously mapped reads can be solved algorithmically. Additional information on the genomic coordinates of target regions and primers used in amplification allows us to evaluate the validity of the mapping of each reading and to exclude readings from the further analysis that do not correspond to the design of the experiment. Objective. To develop an algorithm to minimize the contribution of mapping errors to the spectrum of genetic variants detected by NGS. Material and methods. Using the information on the genomic coordinates of target regions and primers, we have analyzed 30 BAM files obtained by Ion AmpliSeq (targeted multiplex PCR) NGS with commercial Ion AmpliSeq Comprehensive Cancer Panel (15,992 target regions) and Ion AmpliSeq Inherited Disease Panel (10,309 target regions). The algorithm for excluding incorrectly mapped reads was implemented using the Python programming language. Result. We have performed comparison of the initial set of reads and the set obtained after excluding incorrectly mapped reads. This comparison revealed three groups of genetic variants: (1) detectable in both sets of reads, 6072 variants; (2) detectable exclusively in the original set, 127 (the predominant part of these variants is present in most samples and can be interpreted as a result of systematic alignment errors); (3) detectable in the set generated by exclusion of erroneously mapped reads only, 63 (true positive, previously masked variants). Conclusion. The use of additional information on the expected start and end of the read in the targeted study allows to (1) reduce the number of false-positive genetic variants detected due to misleading reads, (2) detect new ones that were not previously detected due to a seemingly low allele frequency, (3) obtain more reliable values of allelic frequencies of the identified variants. The use of our algorithm to exclude the incorrect mapping of the of DNA fragment reads increases the quality of interpretation of the NGS results, which is especially important for DNA diagnostics.

There are various methods for the analysis of chromosomal rearrangements in embryos aborted in miscarriage. Chromosomal microarray analysis is one of the modern diagnostic methods. Studies to determine the diagnostic yield of CMA in comparison to standard karyotyping are of significant scientific and practical interest. Aim. The aim of the present study is to compare the results of CMA and karyotyping of products of conception from women with miscarriage. Materials and methods. A comparative analysis of the two diagnostic methods is based on the study of abortive material from 885 women. In 1st group, 632 women whose products of conception were analysed by CMA were included. The 2nd group comprised 253 women, whose material was directed to a cytogenetic study. Results and discussion. There were no significant differences between study groups in the proportions of samples with a normal and pathological chromosome set. However, the structure of chromosomal abnormalities spectrum in the study groups was different. In both groups, autosomal trisomies were found most frequently - 33.5% in the 1st group and 28.5% in the 2nd group among all the samples. Structural anomalies were significantly more frequent when using CMA - 4.4% of all effective studies in group 1, and only 0.8% (2 cases) in group 2. A higher frequency of polyploidy was revealed during cytogenetic examination. In the 1st group, triploidy was found in 35.8% cases, and tetraploidy in 0.5%. In the 2nd group, triploidy was detected in 10.0%, and tetraploidy - in 5.2% of cases. Conclusions. Traditional karyotyping and CMA have specific relative advantages and disadvantages. The number of chromosomal abnormalities detected using these methods is approximately the same, but the spectum of these anomalies is different. CMA reveals structural rearrangements more often, while karyotyping reveals more cases of multiple anomalies and polyploidy. Identification of structural anomalies has greater clinical significance since it may indicate an unbalanced translocation that is hereditary. The impossibility of detecting balanced translocations with CMA is a limitation of the method that is not as much clinically relevant since it is extremely rare in this type of material.

CFTR mutation analysis is recommended for congenital bilateral aplasia of the vas deferens as well as for cystic fibrosis. Aside azoospermia, the association of CFTR mutations with male infertility is still unclear. A total of 2146 men from couples with reproductive problems were screened for CFTR mutation and intron 8 poly-Т polymorphism (IVS8). Semen analysis was examined for 1820 men. Molecular haplotyping to detect linked TG repeats was performed for IVS8 5T cases. Among 5T alleles only 5T-12TG and 5T-13TG were classified as mutations. Our data showed that 12 patients were compound heterozygotes (all azoospermic) and 4.2% patients were carriers of one mutation. CFTR mutation frequency was significantly higher for azoospermia group to compare with oligozoospermia, severe oligozoospermia, asthenozoospermia and normozoospermia groups. For couples in which man had compound genotype we analyzed infertility threatment accomplished in our clinic (N = 8): 13 IVF-ICSI cycles (in vitro fertilization and intracytoplasmic sperm injection) and two artificial inseminations with donor sperms. Acceptable quality testicular sperms for ICSI have been received by testicular biopsy in all cases. Pregnancy and delivery were achieved for 7 couples.

The study presents the results of a complex medical and population genetic study of hereditary skeletal disorders (HSD) in the child population of 12 districts of the Rostov Region (RR). The aim of the study was to perform genetic and epidemiological analysis of genetic load and diversity of HSD in the child population of RR; as well as to evaluate the role of the genetic structure of RR in the differentiation of the HSD load values in the child population in 12 districts of the RR. Materials and methods: The total size of the investigated population of 12 districts of RR is 101845 children (46356 urban and 55489 rural). A load of autosomal dominant (AD), autosomal recessive (AR) and X-linked (XL) HSD is calculated. Results: the total genetic load of HSD among child population of the RR was 2.47 ± 0.16/1,000 (1:404 children). The differentiation in the values of the load (AD and AR pathology) was identified both between districts and within the districts, as well as between the urban and rural populations. A correlation analysis of genetic load and values of random inbreeding was conducted to determine the reasons for the differences found. The nosological spectrum of the most frequent forms of HSD in the child population of the RR is described. Conclusion: the influence of the genetic structure of the studied populations (in terms of subdivision and migration characteristics) on the values of the genetic load of HSD is shown. Comparative analysis of a total load of HSD in child and adult populations in different districts showed the prevalence of the hereditary load of HSD in the child population over the adult population in 0.5-3.5 times.

Population and genetic structures of the Adyge-Khablsky district of the Karachay-Cherkess republic were investigated. The region is characterized by a multi-ethnic population composition, and the different ethnic group sizes do not exceed half the population of the district. Low inbreeding, low endogamy, high level of population miscegenation were detected.

Nonsyndromic sensorineural hearing loss (NSHL) is a hereditary hearing impairment without other pathological symptoms (isolated), caused by damage to the sound-perceiving apparatus. NSHL is genetically heterogeneous, but on average, about 50% of cases of autosomal recessive NSHL is caused by mutations in the GJB2 gene. Marriages between hard-of-hearing people are a common occurrence in modern society, and the number of such marriages is increasing every year. At the same time, a growing interest in genetic testing was shown in couples consisting of assortative deaf marriages. On the example of two pedigrees, in which several assortative marriages were observed, the problems of medical genetic counseling of patients with hearing loss are analyzed taking into account the possibilities of confirmatory DNA diagnosis. The importance of molecular genetic examination for clarifying the form of the disease and determining the genetic risk for different types of marriages is demonstrated.