<unk>  is a rare disease, with an annual incidence that varies in different populations. Estimates of incidence (new cases per million people) range from 3.7 to 43 in the United Kingdom and Europe, 7.2 in Japan, 10.9 in Taiwan, 12.0 to 22.8 in Australia, 13.9 to 21.0 in the United States, and 21.2 in Buenos Aires. The interval of peak onset starts at age 30 and ends at age 50. Globally, estimates of prevalence vary from 31.0 to 658.6 affected people per million.<unk>  sclerosis has a female:male ratio of 3:1 (8:1 in mid- to late childbearing years). Incidence is twice as high among African Americans. The Choctaw Native Americans in Oklahoma have the highest prevalence in the world (469 per 100,000). The disease has some hereditary association. It may also be caused by an immune reaction to a virus (molecular mimicry) or by toxins.
Systemic scleroderma
Scleroderma
Chilblain lupus erythematosus
Discoid lupus erythematosus
Tumid lupus erythematosus
Mixed connective tissue disease
Lupus erythematosus
Sjögren syndrome