The Birt-Hogg-Dubé cancer predisposition syndrome: Current challenges.

Birt-Hogg-Dubé is a rare syndrome in which carriers of germline mutations in the FLCN tumor suppressor gene are at risk of renal cell carcinoma of all histologies, most often of the chromophobe or hybrid chromophobe-oncocytoma type. Non-oncological manifestations such as lung cysts, pneumothoraces and skin fibrofolliculomas are also common. How germline mutations in a single gene can cause such different clinical features is intriguing and not fully explained, but involvement of the mTOR (renal cell carcinomas, lung cysts) and WNT (fibrofolliculomas) pathways has been described. Given the rarity of the condition, frequent exchanges of ideas between expert teams from around the world, multicentre international collaborations, and interactions between patients and researchers are essential. These needs are fulfilled through dedicated international symposia held every one to two years and through online resources aimed at patients and relatives.