FLCN and Birt-Hogg-Dubé syndrome: FLCN gene encodes the folliculin protein, which could act as a tumor suppressor, and its germline or somatic mutation may be associated with different kinds of cancers, such as fibrofolliculomas, lung cysts, renal tumors, or renal neoplasia in Birt–Hogg–Dubé (BHD) syndrome.