The role of PTCH1 has been further demonstrated in knockout mice: mice heterozygous for PTCH1 null mutation showed essential features observed in patients with Gorlin syndrome, such as malignant tumors (medulloblastomas, rhabdomyosarcomas, basal cell carcinomas) and developmental defects, such as spina bifida occulta [45,46,53]. Here, PTCH1 is linked to basal cell carcinoma.