[Rheumatic diseases and sex differences].

Recently a concept of "sex differences" in medicine has been spreading. It is well known that autoimmune diseases, especially rheumatoid arthritis or systemic lupus erythematosus mostly affect women, and it is clear that there is a strong sex differences in many rheumatic diseases. Sex difference influences to progression or prognosis of the disease. Although the mechanisms of sex difference are not clear, the influence of sex hormones or sex chromosomes which gives immune system is partially elucidated. In addition, sex hormones may become the future new treatment target, and progress in the study regarding this event is expected in the future.