Molecular genetic studies of multiple sclerosis in the portuguese population.

Multiple sclerosis (MS) is a chronic neuroinflammatory autoimmune disease believed to arise from complex interactions of both environmental and genetic factors. As in other complex diseases with autoimmune features, a genetic association with the human leukocyte antigen (HLA) complex is well documented. Association and genome-wide studies were performed in Portuguese patients with MS over several years. Genes such as HLA-DRB1, HLA-A, HFE, TNFA, CTLA-4, PTPN22 and ApoE were investigated. ApoE, PTPN22 1858T, CTLA-4 -318C, TNFA-308A, HFE C282Y and TLR9 T-1237C polymorphisms were not shown to be associated with the development of MS. The HLA-DRB1*15 allele was confirmed as the major genetic marker for susceptibility to MS. The presence of HLA-A*02 and TNFA -238A alleles decreased the risk of developing MS. Patients carrying the HFE C282Y variant seem to have a worse prognosis. The HLA-DRB1*15 and PTPN22 1858T variants were associated with a better outcome in this population.