Sarcoidosis is a rare systemic granulomatous disease that mainly affects young to middle aged adults, and more severely affects African Americans than Caucasians. The etiology of sarcoidosis is not yet known, and epidemiological studies have only identified general risk factors including age, sex, race, and family history. Sarcoidosis may also be influenced by environmental factors, although the particular environmental agents have not yet been clearly defined. While previous studies have provided evidence for familial clustering, little is known about the genes that influence predisposition to sarcoidosis.