Neurofibromatosis type 2 is a rare genetic disorder caused by pathogenic mutations in the NF2 tumor suppressor gene which encodes a protein called merlin. This review describes the structure, functions, and post-translational modifications of merlin, highlights clinical features and known genotype-phenotype correlations of neurofibromatosis type 2, and provides information on the merlin binding sites and the functional contribution of mutations they harbor, which lays the basis for personalized therapy for neurofibromatosis type 2.

Introduction. Primary mitochondrial disorders (PMD) are a group of clinically and genetically heterogeneous group of diseases characterized by a defective structure and functions of the Oxidative Phosphorylation System (OXPHOS). Despite the advantages of the next generation sequencing, diagnosis of PMD is still challenging. There is no currently available biomarker with high specificity and sensitivity. But the level of metabolites reflecting the defective OXPHOS is needed for making of a diagnosis of PMD. Aim: to reveal the level and spectrum of urine organic acids among patients with confirmed diagnosis (by molecular-genetic analysis) of PMD and to estimate the diagnostic value of the test. Methods. We measured 72 different metabolites in 84 urine samples from patients with PMD by GC-MS (7890А/5975С, Agilent Technologies, USA). Results. In 66/84 cases among the patients, we detected the abnormal level of urine organic acids. We observed a unique spectrum of metabolites in the patients with DGUOK-associated hepatopathy (abnormal levels of lactate, pyruvate, 3-hydroxybutyrate, and at the same time 4-hydroxyphenyllactate and 4-hydroxyphenylpyruvate). Using ROC-analysis one of the most informative biomarkers was 3-hydroxybutyrate. But due to the lack of specificity, it could not be classified as a valuable biomarker for PMD. The high level of pyruvate and 4-hydroxyphenyllactate could be taken into account to make a diagnosis of PMD

In this study, we analyzed the association of rs8078424 (chr17:59873104) with the risk of advanced carotid atherosclerosis and disease-related traits. We also assessed the association of this genetic variant with the expression of MIR21 gene in peripheral blood leukocytes of patients. Methods. A group of cases included patients with advanced carotid atherosclerosis who had artery stenosis with 80% or more by ultrasound examination (n=104). We used two control groups. Resident population of Tomsk was the first group (n=161). A second group consists of relatively healthy individuals who had non-hemodynamically significant carotid atherosclerosis (24% or less; n=84). Genotyping of rs8078424 was performed using MALDI-TOF mass spectrometry on a Sequenom MassARRAY® (USA) platform. The expression level of the MIR21 gene in peripheral blood leukocytes was assessed by droplet digital PCR on a QX200 Droplet Digital PCR System (Bio-Rad). Results. The GG rs8078424 genotype was found to be protective against of advanced carotid atherosclerosis (OR=0.023, 95%CI:0.08-0.62; p=0.003) and associated with a lower level of total cholesterol in the serum and increased MIR21 gene expression in peripheral blood leukocytes of the patients. Potential molecular mechanisms of the association of rs8078424 with atherosclerosis include alteration of transcription factors binding sites (FOXP1, SOX18, GATA3, HOXD9, HOXD10, and C/EBPalpha) as well as relationship with the MIR21 gene expression in cells of target organs. Conclusion. The polymorphism of the 17q23.1 locus (in the region of the TUBD1, VMP1/MIR21 genes) is of interest for a more detailed study of susceptibility to cardiovascular diseases in the context of epigenetic mechanisms in single cells of the target organs.

Background. The software provided by the manufacturers of automatic genetic analyzers, in most cases, allows an adequate analysis of the results of Sanger DNA sequencing for templates with a nucleotide composition close to the equivalent. However, to consider the results of sequencing of templates with non-equivalent nucleotide composition, it is necessary to analyze electrophoregrams with preservation of primary information on the intensity of fluorescence signals. This is especially important for the sequencing of DNA modified with sodium bisulfite. Aim: to develop and validate in the practice of scientific research a computer program that ensures adequate analysis of electrophoregrams of Sanger DNA sequencing based on preservation of the primary data and on accurate determination of baselines in the spectral channels of individual nucleotides. Methods. The SeqBase program is written in C#, the programming platform .NET Framework 4.0, and runs in the CLR (Common Language Runtime) for Windows operating systems. SeqBase installation package address is http://www.epigenetic.ru/projects/seqbase. Results. A computer program has been developed designed to analyze the primary results of Sanger sequencing (chromatograms of capillary electrophoresis) obtained from automatic genetic analyzers and presented in files of the ABIF (*.ab1) format, which provides the following functions: 1) viewing the original electrophoregrams both in general form and separately by spectral channels; 2) cropping the area of analysis; 3) signal smoothing; 4) manual setting of the baseline for each of the spectral channels; 5) convergence of baselines on all channels; 6) manual correction of the mobility of DNA fragments depending on the type of fluorescent label of the terminating nucleotide. The program has been successfully tested in a number of studies, the results of which have been published in peer-reviewed scientific journals. Conclusion. The use of the SeqBase program is advisable for the analysis of the results of Sanger sequencing of DNA templates with non-equivalent nucleotide composition, especially those modified with sodium bisulfite, to avoid false results and to clarify quantitative estimates.

The results of clinical and molecular genetic study of the patient with psychomotor delay, phenotype abnormalities and multiple congenital malformations of systems and organs are presented. A standard cytogenetic study determined a double translocation between chromosomes 2 and 6 and chromosomes 7 and 11, confirmed by the FISH method. Chromosomal microarray analysis revealed a deletion of 6q14.1 region at the break point on the long arm of chromosome 6. The deletion involves several dozen genes, including PHIP, FILIP1, MYO6, HTR1B, IMPG1, EVOLV4, TENT5A genes, which are most likely associated with clinical symptoms in the patient.

Single-gene CNVs were observed in 4.4% of patients with intellectual disabilities and developmental delay and were characterized by such criteria as type (deletion/duplication), localization, and origin. It has been shown that not all single-gene variants identified by aCGH can be confirmed by real-time PCR.

The presence of concomitant chromosomal variants in the genome of a patient or an asymptomatic carrier of aberrations may lead to phenotypic variability of pathogenetically significant CNV. It is supposed, that multiple CNVs has a modifying effect, which can be cumulative or compensatory. The risk associated with a particular CNV changes accordingly. This is of fundamental importance for genetic counseling.

Deletions on the X chromosome can lead to serious birth defects. Deletions in Xq21 cause various congenital defects in males including choroideremia, deafness and mental retardation, depending on their size and gene content. Only a limited number of patients with Xq21 deletions has been reported. It has been shown that deletions of the adjacent Xq21 genes, including the POU3F4, CHM and ZNF711 genes, can lead to deafness and mental retardation syndrome and choroideremia. Despite the severe symptoms exhibited by male probands, most female carriers are asymptomatic or exhibit only a mild phenotype. The article presents the clinical and molecular-cytogenetic characteristics of a case of deletion of the Xq21.1-q21.31 region of chromosome X, revealed during chromosomal microarray analysis in a patient with delayed psycho-speech development, facial dysmorphisms and hearing loss. The same deletion was found in an apparently healthy mother. Our study confirms the causative effect between the Xq21 deletion in males and choroideremia, deafness and mental retardation.

Wilson’s disease is a rare autosomal recessive disorder characterized by abnormal accumulation of copper in the liver, brain, and other tissues. Wilson’s disease differential diagnosis is a difficult task due to the pronounced clinical heterogeneity. This emphasizes the importance of developing both new diagnostic methods and improving existing ones. As part of this study, we compared clinical diagnostics with the results of molecular genetic studies. We analyzed 42 patients with suspected Wilson’s disease. The biochemical parameters copper metabolism values were assessed (serum ceruloplasmin concentration, liver copper content, urinary copper excretion, alkaline phosphatase, total bilirubin, AST, ALT) according to the Leipzig quantitative scale. We used genomic DNA for molecular genetic analysis. Regions of interest in the genome was enriched using long-range PCR. The Nextera DNA Flex kit (Illumina, USA) was used to prepare DNA libraries. Sequencing was performed on an Illumina MiSeq device (Illumina, USA). As a result of the study, in 62.5% of cases in patients aimed at confirming the diagnosis (according to the Leipzig quantitative scale), we found mutations in the ATP7B gene, which confirms the value of a comprehensive diagnosis according to the Leipzig quantitative scale, taking into account the clinical symptoms and copper metabolism laboratory parameters.