Gm allotypes in multiple sclerosis: influence susceptibility in HLA-DQwl-positive patients from the North-East of Scotland.

From the Grampian region of Scotland, 198 patients with MS and 128 normal individuals were typed for allotypes of the Gm system which encode for the constant region of IgG heavy chains. No significant independent association between a given Gm allotype or phenotype and susceptibility to MS was observed for the group of patients from this region. This was also the case when patients were classified according to sex, clinical course, and disease progression. However, a significant association was found between the Gm phenotype, Gm (3;5, 10, 11, 13, 14), and HLA DQwl in patients with MS. The relative risk of developing MS for individuals who carried both Gm (3;5,10, 11,13,14) and HLA DQwl was nearly five times greater than for individuals with neither determinant. These findings suggest that in the presence of HLA DQwl, genes associated with the Gm (3;5,10,11,13,14) phenotype have an important contributory influence on susceptibility to MS. The additive effects of Gm and HLA on susceptibility to MS would be one possible reason for the lack of a complete association between MS and a single genetic locus.