Systemic lupus erythematosus: genes versus environment in high risk populations.

The risks of systemic lupus erythematosus (SLE) are known to vary considerably with ethnic origin. Prevalence of lupus is increased in African-American, Afro-Caribbean, Native American, Asian Indian, Polynesian and Chinese populations compared with people of European descent. The consistency with which high prevalence of lupus occurs in these populations descent living in different environments suggests that genetic factors are likely to underlie the high risk in this group. However the increased risk of lupus in high risk groups such as West Africans compared with Europeans does not appear to be accounted for by differences in allele frequencies at any of the loci where associations with SLE have been found, including those in the HLA region. To date the contribution of environmental factors to a complex disease such as lupus is still not fully understood. This article explores possible environmental risk factors for SLE in high risk ethnic groups. Smoking, occupational exposures to silica and exposure to infection in childhood may explain some non-genetic risk factors for SLE in these groups.