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.