BACKGROUND:

Sarcoidosis is a multisystem, granulomatous inflammatory disease of unknown etiology. Hereditary susceptibility to sarcoidosis is suggested by reports of familial clustering and a higher prevalence in certain ethnic groups, particularly African-Americans. Over four hundred kindreds been reported in the medical literature and these investigators have recently described 101 families and shown that African Americans have a higher prevalence rate of familial sarcoidosis than Caucasians (19 percent vs. 5 percent). The reasons why sarcoidosis clusters in families or the role of genetic factors in this disease are not known.

DESIGN NARRATIVE:

The study was carried out in African American families ascertained through 400 African American sarcoidosis patients evaluated at the Henry Ford Health System. They were tested for association of sarcoidosis with markers for candidate genes using the affected family-based control method and tested for possible environmental risk factors and genetic mechanisms of disease transmission by performing a segregation analysis in African American families.

A strong association of one or more of the candidate genes with sarcoidosis or an indication of major gene segregation for the disease, provided the basis for future linkage studies. Investigating the hereditary susceptibility of sarcoidosis was best done in African Americans, because of the greater severity and occurrence of disease in this population. Once the reasons for familial aggregation of sarcoidosis are determined, the etiology of this disease will be better understood and it should be possible to design new approaches to prevention and treatment.