Peptic ulcer disease is a chronic, cyclically disease proceeding with diverse clinical picture and ulceration of the mucous membrane of the stomach and/or duodenum during periods of exacerbation. This is one of the most common pathology of the gastrointestinal tract, which affects about 10% of the total world population. The most probable cause of ulcerative lesions of the mucous membrane of the stomach or duodenum consider infection with the bacterium Helicobacter pylori, but ulcerogenicity it depends on a large number of endogenous and exogenous risk factors. Numerous studies conducted in different countries show that the propensity of peptic ulcer disease is genetically determined, there are plenty of candidate genes, which protein products are involved in the pathogenesis of this disease. The study of molecular-genetic bases of peptic ulcer is a necessary condition for the development of new approaches to the diagnosis and optimal treatment. The aim of this work is a review of the current state of knowledge of peptic ulcer disease and to summarize latest achievements in molecular genetics of the disease. 

Diversity of monogenic hereditary diseases (MHD) in the population of eight districts of the Republic of Tatarstan (RT) is reviewed. The number of the investigation population was 264,310 people. The analysis was performed for the entire population of the region, and separately for the representatives of the titular nation — Tatars. Tatar population (209,265 people) represented by three basic ethnographic groups — the Kazan Tatars (Arsky, Athninsky, Kukmorsky districts) Mishars (Buinsky, Drozhzhanovsky) and Teptyars (Aktanysh, Muslumovsky and Menzelinsky). Nosological spectrum of MHD was 256 diseases: 135 with an autosomal dominant (AD) mode of inheritance, 97 with autosomal recessive (AR) and 24 X-linked. The prevalence of the MHD, frequent and rare nosological forms, the accumulation of some diseases in subpopulations was determined. For 38 MHD (211 patients) diagnostics was carried out for DNA. A comparison of the diversity of the MHD with previously published data on the genetic and epidemiological studies of the European part of Russia: Kirov, Kostroma, Tver, Bryansk and Rostov regions, Krasnodar Kray and the Republics of Chuvashia, Bashkortostan, Mari El, Udmurtia and Adygea. 

Here we present the results of the hearing loss genetic component study caused by mutations in the GJB2 (Cx26) gene. The study was conducted in 201 patients from the Republic of Tuva with congenital or early onset severe-profound sensorineural hearing loss. The GJB2 gene recessive mutations p.W172C (c.516G>C), IVS1+1G>A (с.-23+1G>A), c.235delC, p.V37I (c.109G>A), c.299_300delAT, c.35delG) in homozygous, compound heterozygous or heterozygous mutation states were identified in 70 patients (34.8% of patients), 38 of whom (18.9%) had two GJB2-mutation, and 32 (15.9%) — only one GJB2-mutation. Mutational spectrum of the GJB2 gene in studied Tuvinian patients was characterized by the presence of five mutations (p.W172C, IVS1+1G>A, c.235delC, p.V37I, and c.299_300delAT) and GJB2 gene polymorphic variants p.V27I (c.79G>A), p.E114G (c.341A>G), p.V153I (c.457G>A), p.F191L (c.571T>C), p.I203T (c.608T>C), common in the Asian regions while the only mutation c.35delG characteristic for Caucasians has been found in Russian patients. The frequencies of mutations p.W172C, IVS1+1G>A, c.235delC, p.V37I, and c.299_300delAT among all mutant chromosomes in examined Tuvinian patients were 51.49%, 38.61%, 4.95%, 2.97%, and 1.98%, respectively. Total carrier frequency of recessive GJB2 mutations in Tuvinian population sample (n = 121) was 11.57% (p.W172C — 4.96%, IVS1 +1 G>A — 4.13%, p.V37I — 2.48%, respectively). We detected GJB2 mutations in patients that had a history of various environmental etiological factors, presumably leading to their hearing loss. This strongly suggests the necessity for genetic testing in such group of patients as well. Familial cases of «Cx26-negative» hearing loss identified in the Republic of Tuva suggests the presence of other, yet unidentified, genes associated with this pathology. The proportion of patients with hearing loss due to the presence of two recessive GJB2 mutations of the gene is 18.9%, which is a minimal estimation of the genetic component in etiology of hearing loss in the Tuva population. 

By means of microsatellite analysis we have evaluated allelic status of eleven chromosome loci for which allelic imbalance (AI) had never been described in glioblastoma. Two of the eleven loci, 18q11.2 and 21q21.1, revealed no allelic imbalance in 108 glioblastoma samples. However, AI was identified at 2q31.2, 3p25.1, 5q14.3, 6p21.1, 7q21.2, 9q21.33, 12q21.33, 16p13.12, 19p13.2 with the frequencies of 5,0%, 19,0%, 11,1%, 3,8%, 28,6%, 3,6%, 5,9%, 9,6%, 17,0%, respectively, demonstrating the necessity to expand molecular genetic studies of glioblastoma. To test if our sampling is representative we have analyzed 8q21.3 and 14q13.3 loci where AI had been previously described. AI at these loci was confirmed with the frequencies of 15.8% and 42.3%, respectively, which is consistent with the previously published data. We discuss potential candidate genes located in the chromosomal loci for which LOH has been identified in this study.