Mediterranean and Amerindian MHC class II alleles are associated with multiple sclerosis in Mexicans

Objectives - Human leukocyte antigen (HLA)-DRB1, DQA1, DQB1 allele typing was performed in Mexicans Mestizos with multiple sclerosis ( MS) to de. ne the HLA class II alleles associated with the disease in this population. Methods - Patients (n = 51) diagnosed according to the Poser criteria and a group of 173 unrelated healthy subjects were studied. PCR-SSOP and PCR-SSP were used for genotyping. Results - Fifty five percent of the patients were females. The mean age at disease onset was 27 years. A relapsing - remitting disease was the most frequent type of MS (67%). A significant association of DRB1*0403 (OR = 5.68) with MS was shown. DRB1*0802 was also involved in susceptibility (OR = 2.41). An excess of DRB1*0802 homozygotes was observed in patients (P = 0.005), this genotype being in genetic equilibrium in controls. Conclusions - Two novel class II associations are described in Mexicans with MS: DRB1*0403 and DRB1*0802. Both alleles share with DRB1*1501, valine-86 and negatively charged amino acids, in the DRB1-anchoring motif of pocket 4.