title: Sex ratio and rheumatic disease.
abstract: Autoimmune diseases are said to have high female/male (F/M) ratios, but these ratios are imprecise. Published definitions and classifications of autoimmune diseases differ substantially, as do the F/M ratios themselves. Imputed causality of autoimmune diseases requires better precision. Some thyroid, rheumatic and hepatic diseases consistently have high F/M ratios, but marked differences exist in the reported quantity of the ratios. Other autoimmune diseases have low F/M ratios. Because F/M ratios reflect incidence and not severity of disease, gonadal hormones, if they play a role, must do so through a threshold or permissive mechanism. Sex differences related to environmental exposure, X-inactivation, imprinting, X or Y chromosome genetic modulators, and intrauterine influences remain as alternate, theoretical, explanations for sex differences of incidence. The epidemiology of the sex-discrepant autoimmune diseases--young, female--suggests that an explanation for sex discrepancy lies in differential exposure, vulnerable periods, or thresholds, rather than in quantitative aspects of immunomodulation.
authors.affiliation: Barbara Volcker Center, Hospital for Special Surgery, Joan and Sanford I. Weill Medical College, Cornell University, New York, USA. LockshinM@hss.edu
authors.forename: M D
authors.initials: MD
authors.lastname: Lockshin
mesh_terms: D000367:Age Factors; D000818:Animals; D005260:Female; D006801:Humans; D008297:Male; D051379:Mice; D051381:Rats; D012216:Rheumatic Diseases / Q000453:epidemiology / Q000209:etiology*; D012307:Risk Factors; D017678:Sex Distribution; D012737:Sex Factors; D012744:Sex Ratio