A significant number of ovarian malignancies are hereditary (up to 30% of all neoplasms result from a high genetic predisposition). At least 16 candidate genes for hereditary ovarian cancer are known, and with the introduction and widespread use of genome-wide sequencing, an increasing number of genes and genetic variants are potentially involved in the pathogenesis of familial forms of the disease, although the contribution of these genes to the development of hereditary ovarian cancer . The detection of specific mutations in a number of ovarian cancer candidate genes in healthy women can justify not only more intensive and personalized surveillance programs, chemoprophylactic approaches and / or preventive operations, but also can provide fundamental knowledge about the pathogenesis of tumor development. This article describes the clinical features of hereditary ovarian cancer due to mutations in the key candidate genes (BRCA1, BRCA2, TP53, BARD1, CHEK2, RAD51, PALB2). The main types of mutations in BRCA - associated ovarian cancer, age-related features and survival rates are described. It was shown that the majority (approximately 65-85%) of hereditary ovarian tumors account for germline mutations in the BRCA1 and BRCA2 genes. It is believed that mutations in these genes lead primarily to gynecological oncological diseases in estrogen-sensitive target organs, however, according to some reports, there is also the likelihood of cancer of the stomach, colon, endometrium, pancreas, skin melanoma, bladder, head and neck tumors. Approximately 6% of hereditary OC is accounted for by germline mutations of the BARD1, BRIP1, CHEK, MRE11A, MSH6, NBN, PALB2, RAD50, RAD51C and TP53 genes, the protein products of which are involved in the restoration of homologous recombination. Medium and low penetrant genes individually carry only minimal risk, but due to the multiplicative and / or cumulative effects, they can cause a relatively high risk for carriers. The article describes in detail the oncogenesis of ovarian cancer due to a mutation in the genes for the restoration of the mismatch MMR - Lynch syndrome, which is the second leading cause of hereditary ovarian cancer and makes up from 2% to 15% of all cases of the disease. Other proteins encoded by the RAD51, RAD50, ATM, MRE11 and PALB2 genes that interact with the products of the BRCA1 / 2 genes in the mechanism of homologous recombination repair are also described in detail

As pregnancy is a stressful load for a woman, any stress-resistance factor is relevant to it. According to recent reports, ribosomal gene copy number in the genome is associated with the individual stress-resistance. We determined copy numbers of ribosomal DNA (rDNA) in genomes of pregnant women with normal and complicated pregnancy, and women after in vitro fertilization (IVF) procedure. We also measured the contents of GC-rich rDNA in cell-free DNA (cfDNA) derived from normal controls and complicated pregnancy cases. We have shown that genomes of more than a half of DNA samples from women with pregnancy pathology harbor either more, or less rDNA copies than any woman from the control group. We also found higher rDNA contents in cfDNA isolated from complicated pregnancy cases suggesting the presence of a permanent cell death process in pathology cases. A principal conclusion can be made: women with low rDNA copy numbers and with very high numbers can have higher cell death rates and belong to the risk group. The parameter «rDNA copy number in woman’s genome» can be an additional prognostic marker for eventual pregnancy complications in the woman. The numbers of rDNA copies in the genomes of women with failed IVF attempts was significantly lower than in the genomes of patients with succesfull outcome, suggesting that rDNA copy number in the genome is one of the factors that affect the success of the IVF procedure. If the individual rDNA copy number is under 330, the risk of IVF failure is high. Further studies are warranted.

Objective: hereditary spastic paraplegias (HSP) are a heterogeneous group including about 80 forms: SPGs (Spastic Paraplegia Gene) numbered chronologically. Massive parallel sequencing MPS greatly improved possibilities of new SPGs disclosure and of practical DNA diagnostics. First Russian HSP complex investigation of HSP using MPS is being performed in FSBI PCMG. By now, the group of genetically diagnosed cases numbers 114 families with 20 different SPGs, including rare autosomal recessive forms poorly known to geneticists and neurologists. Aim: to present first Russian cases of rare autosomal recessive (AR) forms: SPG5, SPG26, SPG35, and SPG39. The genes, CYP7B1, B4GALNT1, FA2H, and FA2H correspondingly, are involved in lipid metabolism. Materials: initial group: about 200 Russian families with preliminary clinical diagnosis of HSP or alike disorders; index group: 114 SPG-confirmed families; paper material: the four families. Methods: clinical investigation, genealogical analysis; molecular methods: custom MPS-panel “paraplegias” (63 genes), Sanger sequencing, multiplex ligation-dependent probe amplification MLPA (selectively), whole-exome sequencing WES (selectively); bioinformatic analysis. Results. Subgroup of AR SPG included 22 families/12 forms. SPG5, 26, 35, 39 were detected in single families. SPG5: a 17-year-old youth in a Russian family; onset in 15 years, moderate spastic paraparesis, mild ataxia; CYP7B1 genotype: two earlier reported mutations .334С>T (p.Arg112Ter) и c.1190C>T (p.Pro397Leu) in the patient and in unaffected younger sister (preclinical stage), parents - heterozygous carries. SPG26: a 13-year old boy in a Russian non-consanguineous family; early-childhood onset, slowly progressing paraparesis, dysarthria, cognitive and behavioral impairment; B4GALNT1 genotype: novel homozygous mutation c.1514G>C (p.Arg505Pro) in the boy, heterozygosity in parents; homozygosity for a very rare gene (14th SPG26 world case) in a Russian non-consanguineous family is unusual. SPG35: a 5-year-old boy in a Sibirian ethnically mixed family (Russian mother, father of Tatar-Buryat ethnicity); onset in 4 years, rapidly progressing paraparesis with no other signs, normal MRI; FA2H genotype: reported earlier с.805С>T (p.Arg269Cys) / novel c.106C>T (p.Leu36Phe). SPG39: a 10-year-old boy in a Russian-Tatar family; onset in 5 years, slowly progressing paraparesis with no other signs; PNPLA6 genotype: reported earlier intronic с.199-2A>T novel c.2033G>A (p.Gly678Asp), parents - heterozygous carriers. Conclusions. HSP in Russian patients present a wide spectrum including rare AR SPG in non-consanguineous Russian families and in families of mixed ethnicity. Our SPG5, SPG26, SPG35 and SPG39 cases are first in Russia; of 7 mutations detected in the 4 genes 3 mutations were novel. MPS is method of choice in DNA diagnostics of heterogeneous disorders like HSP.

The article presents a clinical case of Turner syndrome (TS) in a mother and her two daughters. Standard cytogenetic examination using by GTG-staining technique found mosaic karyotype with two cell lines, one clone with monosomy X (45,X) and other one with ring X-chromosome - 46,X,r(X)(p22.3q28). Fluorescent in situ hybridization revealed gonosomal mosaicism mos X/X,r(X) in peripheral blood lymphocytes and buccal epithelial cells in all patients. There number of cells containing ring X chromosome were similar in lymphocytes (8-11%), and were more varied in buccal epithelium (26-47%) between patients. Analysis of X chromosome inactivation (XCI), performed in the mother and her eldest daughter, revealed skewed inactivation of ring X chromosome. The patients had a similar phenotype signs characterized to Turner syndrome, but fertility was preserved at least in the mother and her eldest daughter. Reported in the literature familial TS cases with ring X chromosome are reviewed.