Background: The myelin basic protein (MBP) gene may confer genetic susceptibility to multiple sclerosis (MS). The association of MS with alleles of the (TGGA)n variable number tandem repeat (VNTR) 5' to the MBP gene is the subject of conflicting reports.
Objective: To study possible MS association with VNTR alleles of MBP gene in ethnic Italians and ethnic Russians.
Methods: Two hundred sixty-nine unrelated patients with definite MS and 385 unrelated healthy control subjects from Italy and Russia were genotyped for the MBP VNTR region and for the human leukocyte antigen (HLA) class II DRB1 gene. The phenotype, allele, and genotype frequencies for two groups of MBP alleles were determined. Patients and control subjects were stratified according to HLA-DRB1 phenotypes.
Results: The distribution of MBP alleles and genotypes in the two ethnic groups, including both MS patients and control subjects, was very similar. When MS patients and healthy control subjects were stratified according to HLA-DRB1 phenotypes, a significant association of MS with MBP alleles was found only in the DR4- and DR5-positive subgroups. A significant association with MBP alleles was also observed in the nonstratified groups, owing mainly to the contribution of the DR4- and DR5-positive individuals.
Conclusion: Polymorphism of the MBP or another gene in its vicinity appears to contribute to the etiology of MS for the subgroups of DR4- and DR5-positive Italians and Russians.