Sexual disparities in the incidence and course of SLE and RA.

Systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) disproportionately affect females compared to males, with female to male prevalence ratios of 7-9:1 for SLE and 2-3:1 for RA. Interestingly, epidemiologic studies indicate that men that develop SLE may have more morbidity than women, but the same is not true for RA. Given the sex and age bias of SLE and RA, sex hormones may influence the pathogenesis of these diseases. However, the ways in which, and to what degree, sex hormones affect disease incidence and severity remain unclear and is the topic of ongoing research. Recent findings have implicated interactions between sex hormones, the immune system, genetic factors, and epigenetic modifications in influencing SLE and RA disease activity. This article reviews current hypotheses regarding the potential impact of sex hormones and genetics on disease pathogenesis, incidence, and severity of SLE and RA.