Sex Differences in Autoimmune Disease

This chapter discusses some autoimmune rheumatic diseases, which mainly affect women. The reasons for sex predominance are unclear. Sex predominance is an epidemiological construct indicating female:male (F/M) incidence ratios; it is not a clinical construct that denotes disease severity. A high F/M ratio of autoimmune diseases supports the hypothesis that estrogen, by modulating the process of immune response controls an illness. However, basic facts regarding F/M ratios are contested and less reliable than assumed; uncited illnesses in which males predominate contradict claims of estrogen control. The chapter discusses that estrogen drives autoimmunity that are demonstrably female predominant, such as thyroid diseases, rheumatic diseases, and hepatic diseases, while failing to account for ankylosing spondylitis, vasculitis, goodpasture disease, juvenile onset diabetes, and inflammatory bowel disease, diseases that are sex neutral or male predominant. Selective citation is possible in part because definitions for autoimmunity differ. Some clinical definitions include high F/M ratios as a relevant characteristic; definitions that focus on the autoimmune process largely ignore the relevance of sex, except insofar as estrogen controls quantitative in vitro response.