Genetic mutations to the gene responsible for the production of Patched, which were identified in patients with both sporadic and hereditary BCC, lead to the loss of the inhibitory effect exerted on Smo by Patched, which in turn leads to upregulation of the end products of the Hh/PTCH/Smo pathway.5,28 TGF-β, 1 of the 2 classes of TGF and an end product of the Hh pathway, normally inhibits proliferation and promotes differentiation of the epithelial cells. This evidence concerns the gene PTCH1 and skin basal cell carcinoma.