[Variability of the MIR196A2 Gene as a Risk Factor in Primary-Progressive Multiple Sclerosis Development].

Multiple sclerosis is a chronic disease of the central nervous system, combining in its pathogenesis both autoimmune and neurodegenerative components, and is characterized by a highly heterogeneous clinical phenotype. Genetic susceptibility to the development of the most common relapsing-remitting course of the disease is extensively studied, while the genetic architecture of the aggressive primary progressive course of multiple sclerosis remains poorly understood. We analyzed the association of polymorphic variants in miRNA genes MIR146A, MIR196A2, and MIR499A with the risk of primary progressive multiple sclerosis one by one and in biallelic combinations with variants of immune-related genes; the analysis was performed in comparison with healthy individuals and with relapsing-remitting multiple sclerosis patients. The allele MIR196A2*C was useful in discriminating between two main courses of multiple sclerosis, one by one and in combination with alleles of the IFNAR2, IL7RA, IL6, PVT1, CD86, CCL5, and PSMB9 genes. The data presented in the current work may be used for the construction of a biomarker panel, to differentiate primary progressive and relapsing-remitting courses of multiple sclerosis on the initial stages of the disease.

A review of genome-wide association studies for multiple sclerosis: classical and hypothesis-driven approaches.

Multiple sclerosis (MS) is a common complex neurodegenerative disease of the central nervous system. It develops with autoimmune inflammation and demyelination. Genome-wide association studies (GWASs) serve as a powerful tool for investigating the genetic architecture of MS and are generally used to identify the genetic factors of disease susceptibility, clinical phenotypes, and treatment response. This review considers the main achievements and challenges of using GWAS to identify the genes involved in MS. It also describes hypothesis-driven studies with extensive genome coverage of the selected regions, complementary to GWASs. To date, over 100 MS risk loci have been identified by the combination of both approaches; 40 of them were found in at least two GWASs and meet genome-wide significance threshold (p ≤ 5 × 10(-8)) in at least one GWAS, whereas the threshold for the rest of GWASs was set in our review at p < 1 × 10(-5). Yet, MS risk loci identified to date explain only a part of the total heritability, and the reasons of "missing heritability" are discussed. The functions of MS-associated genes are described briefly; the majority of them encode immune-response proteins involved in the main stages of MS pathogenesis.

[Polymorphic variants of the immune response genes as risk factors for primary progressive multiple sclerosis]. / Polimorfnye varianty genov immunnogo otveta kak faktory riska razvitiia pervichno-progressiruiushchego rasseiannogo skleroza.

AIM: To analyze the involvement of immune response genes in the pathogenesis of primary progressive multiple sclerosis (PPMS). MATERIAL AND METHODS: This multicenter study included 111 patients with PPMS from the Russian ethnic group. The association of PPMS with genes of immune system was analyzed by the study of polymorphic variants of genes of cytokines and genes of antigen-presenting cells. RESULTS AND CONCLUSION: The genotypes of IL-4 (rs2243250)*C/C and CLEC16A (rs6498169)*G/G were associated with PPMS in Russians. The association between the HLA-DRB1*15 and PPMS found out in other populations was confirmed in Russians.

[Association analysis of cytokine receptors' genes polymorphisms with clinical features of multiple sclerosis]. / Analiz assotsiatsii polimorfizma genov, kodiruyushchikh retseptory tsitokinov, s klinicheskimi kharakteristikami rasseyannogo skleroza.

AIM: To study the association of polymorphisms in the IL2RA and TNFRSF1A genes with severity and early clinical manifestations of remitted multiple sclerosis (MS). MATERIAL AND METHODS: Five hundred and eight patients of Russian ethnicity with bout-onset MS were genotyped for IL7RA (rs6897932), IL2RA (rs2104286) and TNFRSF1A (rs1800693) polymorphisms. Association analysis of the gene variants with disease severity, variants of MS manifestation, and first remission duration was performed. RESULTS AND CONCLUSION: Dividing the MS patients by disease severity, estimated with the MSSS, we found a significant increase in the TNFRSF1A*T/T genotype carriage in patients with milder MS course (MSSS≤3), and, respectively, in the TNFRSF1A*C allele carriage in patients with moderate to severe MS (MSSS> 3). Dividing the MS patients into two groups according to their MS manifestation variants, we revealed a significant increase in the TNFRSF1A*T allele carriage in patients with favorable variants of MS manifestation (optic neuritis or sensory disturbances), and of the TNFRSF1A*C/C genotype in patients with unfavorable variants (motor disorders, brain stem disorders, impaired coordination, pelvic disorders, mental disorders or polysymptomatic onset). No associations with first remission duration were observed. Multi-locus analysis to search for allelic combinations associated with the studied clinical features of MS was applied. In this analysis, a polymorphic variant of CTLA4 gene (rs231775), for which we have previously reported the association of the CTLA4*G allele with short first remission (less than 1 year), was also included. The carriage of biallelic combination (CTLA4*G + TNFRSF1A*C) was associated with short first remission more significantly than the carriage of CTLA4*G by itself. One more biallelic combination associated with short first remission (CTLA4*G/G + IL7RA*T), was identified. No other biallelic combinations significantly associated with the clinical features studied were observed.

GWAS-identified multiple sclerosis risk loci involved in immune response: validation in Russians.

Multiple sclerosis (MS) is a chronic neuro-inflammatory disease of complex etiology. The results of GWAS, a high-throughput method to discover genetic architecture of MS, require replication in independent ethnic groups. We performed a replication study of nine GWAS-identified SNPs in immune response in Russians. Associations of CLEC16A and IL2RA with MS were validated. Besides, we observed the associations of CLEC16A and IRF8 in women, and IL7RA and CD58 in men. With multi-locus association analysis two protective biallelic combinations: (TNFRSF1A*T+CLEC16A*A) and (TNFRSF1A*T+IRF8*A) were identified in women. Associations of CLEC16A*G/G and both biallelic combinations in women with MS survived the permutation test.