Genetic predisposition factors for multiple sclerosis (based on the data from genotyping patients of the Russian ethnic group)

Patients' genotyping of Russian ethnic group with multiple sclerosis (MS) was performed for the first time in two loci of the main complex of histocompatibility: in DR HLA class II (gene DRB1) and in the locus of tumor necrosis factors (TNF). There was no difference in the incidence of alleles groups which correlated with some specificity of DR. Meanwhile TNF-a1 and TNF-a9 alleles were encountered significantly more frequently in patients and TNF-a7 in control group. When all the patients and controls examined were divided into groups in dependence on combination of DR and TNF it was found that relations observed between MS and TNF-a7 and TNF-a9 alleles were displayed much more in individuals which carried alleles of gene DRB1, corresponding to DR15 specificity. These are alleles which are known as the main risk factor of MS in Caucasians. The patients with "protective" TNF-a7 allele were characterized by more favorable course of the disease. Thus highly significant genetic markers were revealed for the first time in region of TNF genes which were associated with increased or decreased risk of MS development at least in Russian ethnic group. There was also possibility of their interaction with group of DR15 alleles of DRB1 gene. One of the markers revealed (TNF-a7) occurred to be bound both with decreased risk of MS and with favorable clinical course, which was observed for genetic markers of MS for the first time. Manifestation of one or another property of TNF-a7 marker depends on the presence of alleles of DRB1 gene which corresponds to DR15 specificity.