Association of the HLA-DRB1*15 allele group and the DRB1*1501 and DRB1*1503 alleles with multiple sclerosis in White and Mulatto samples from Brazil.

Multiple sclerosis (MS) is a multifactorial inflammatory disease that primarily affects the central nervous system. Genes and environmental factors probably interact in MS susceptibility and outcome; however, their roles have not been elucidated yet. The evaluation of the HLA-DRB1 gene in the Brazilian population is of particular interest in evidencing the behavior of HLA-DRB1 alleles in a highly admixed population inserted in an environment of low MS prevalence. The present results suggest that a given HLA-DRB1 allele may exhibit different behaviors, i.e. confer resistance or susceptibility, in response to the environmental and/or genetic (ethnic) backgrounds that characterize a sampled population.