FLCN and lung disorder: In Birt–Hogg–Dubé (BHD) syndrome, individuals are often afflicted with skin tumors, lung disease, and chromophobe RCC due to mutations in FLCN [21] leading to the downstream activation of mTOR, via the loss of negative inhibition by the BHD protein, similarly to how TSC1 and TSC2 complexes downregulate mTOR activity [21].