PTCH1 gene encodes protein patched homolog 1, which is a multipass transmembrane receptor for the hedgehog family of secreted factors. Binding of hedgehog to the receptor relieves its inhibitory action on the transmembrane co-receptor Smoh. PTCH1 protein seems to have a tumor suppressor function, as inactivation of this protein is probably a necessary, if not sufficient step for tumorigenesis. It plays a role in cell growth, cell specialization, and patterning of many different parts of the developing body.

Defects in the PTCH1 protein have been associated with basal cell nevus syndrome, esophageal squamous cell carcinoma, trichoepitheliomas, transitional cell carcinomas of the bladder, as well as holoprosencephaly. Somatic mutations in the PTCH1 gene are associated with a sporadic basal cell carcinoma, medulloblastoma, breast cancer, and colon cancer. Individuals with the 9q22.3 microdeletion have one missing copy of the PTCH1 gene in each cell, which causes the signs and symptoms of Gorlin syndrome. There are other signs and symptoms related to 9q22.3 microdeletions, including delayed development, intellectual disability, overgrowth of the body, and other physical abnormalities.