Gender bias in autoimmune diseases: X chromosome inactivation in women with multiple sclerosis.

The majority of autoimmune disorders are characterized by female predominance. Several mechanisms have been proposed as explanations for this gender bias, among them X chromosome inactivation. An increased frequency of skewed X inactivation has been found in some autoimmune disorders, like scleroderma and autoimmune thyroid disease, and may thus offer a possible explanation for the female predominance. Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system, with pathological features of an autoimmune disorder. The incidence of MS in females is approximately twofold compared to the incidence in males. X inactivation does not seem to be part of the explanation for the gender bias in MS. This paper reviews the possible role of X chromosome inactivation in some autoimmune diseases, and describes a recent study of X inactivation in females with MS.