PTCH1 and skin basal cell carcinoma: Hh ligand-independent tumor was first identified in patients, who harbor germline loss-of-function mutation in PTCH1 (55), with nevoid basal cell carcinoma syndrome (also known as Gorlin syndrome), tending to develop tumors, especially basal cell carcinoma (BCC), medulloblastoma (MB) and rhabdomyosarcoma (56).