Familial risk ratio of sarcoidosis in African-American sibs and parents

While sarcoidosis is thought to aggregate in families, little is known abou t the risk to relatives of sarcoidosis patients. To estimate the familial r isk ratio (lambda) of sarcoidosis in sibs and parents of cases, the authors studied 179 African-American families ascertained through an index sarcoid osis case diagnosed at Henry Ford Hospital in Detroit, Michigan. Among thos e relatives enrolled between 1997 and 1999, 12 of 327 (3.7%) sibs and 11 of 161 (6.8%) parents reported a history of sarcoidosis. The lambda in this s ample of relatives, estimated by computing an age, sex, and race standardiz ed incidence ratio, was 2.24 (95% confidence interval: 1.16, 3.92) for sibs and 2.82 (95% confidence interval: 1.41, 5.05) for parents. For sibs and p arents combined, lambda was 2.49 (95% confidence interval: 1.58, 3.73). Res ults stratified by proband characteristics indicated that lambda was greate r for relatives of younger (lambda = 2.93, 95% confidence interval: 1.52, 5 .12) and male (lambda = 3.98, 95% confidence interval: 1.99, 7.12) probands . A higher lambda was also found for male family members and sibs born late r in the birth order. A Monte Carlo method was also used to estimate lambda , with similar results obtained. Overall, these results indicate that, in A frican Americans, sibs and parents of sarcoidosis cases have about a 2.5-fo ld increased risk for sarcoidosis and that heterogeneity in disease risk ma y exist among family members.