The association between red hair color (RHC) melanocortin 1 receptor genotype, past environmental sun exposure, and risk of multiple sclerosis (MS) was investigated in a population-based case-control study in Tasmania, Australia, involving 136 cases with MS and 272 controls. Increasing summer sun exposure at ages 6 through 10 years was associated with reduced MS risk among those with no RHC variant (p=0.03), but not among those with RHC variant genotype (p=0.15). The association was more evident for women than for men. [1]