Epidemiological studies have highlighted a familial aggregation of multiple sclerosis potentially explained by several environmental and genetic risk factors.1 Family studies assessing risks to relatives of multiple sclerosis patients showed that first-degree relatives are generally at 10–25 times greater risk of developing multiple sclerosis than the general population, but this risk could be lower.2 Several major histocompatibility complex (MHC) loci—especially HLA DRB1*15:01—are the most important genetic risk factors for developing multiple sclerosis with odd ratios around three. Here, HLA-C is linked to multiple sclerosis.