Sex and gender issues in multiple sclerosis

Multiple sclerosis (MS) is universally found to be more prevalent in women than men. This has led to extensive studies of differences in the immune system or nervous system between women and men, which might be caused by the effects of gonadal hormones, genetic differences, and different environmental exposures and modern lifestyle in men and women. We review the effects of sex and gender from a genetic, immunological and clinical point of view. We discuss the effects of sex on the clinical expression of MS and responses to therapy, as well as issues concerning pregnancy.