Increased prevalence of renal disease in systemic lupus erythematosus families with affected male relatives.

OBJECTIVE: To distinguish familial differences from sex-related differences in the clinical manifestations of systemic lupus erythematosus (SLE). METHODS: A total of 372 affected individuals from 160 multiplex SLE pedigrees were analyzed. Twenty-five of these pedigrees contained at least 1 affected male relative. Comparisons of the presence of each of the 11 1982 American College of Rheumatology criteria for SLE were made between female family members with affected male relatives and those without affected male relatives, using Fisher's exact tests. RESULTS: The presence of renal disease was significantly increased in female family members with an affected male relative when compared with those with no affected male relative (68% and 43%, respectively; P = 0.002). This trend remained after stratifying by race and was most pronounced in European Americans. A familial basis for differences in hematologic and immunologic manifestations was also suggested, while arthritis and dermatologic features appeared to be most influenced by sex. CONCLUSION: Our results demonstrate that the increased prevalence of renal disease previously reported in men with SLE is, in large part, a familial rather than sex-based difference, at least in multiplex SLE families. Distinguishing familial from sex-related differences may facilitate efforts to understand the genetic and hormonal factors that underlie this complex autoimmune disease.