UCLA Department of Human Genetics

Gorlin syndrome, also known as nevoid basal cell carcinoma syndrome, is a condition that affects many areas of the body and increases the risk of developing various cancerous and noncancerous tumors. In people with Gorlin syndrome, the type of cancer diagnosed most often is basal cell carcinoma, which is the most common form of skin cancer. Individuals with Gorlin syndrome typically begin to develop basal cell carcinomas during adolescence or early adulthood. These cancers occur most often on the face, chest, and back. The number of basal cell carcinomas that develop during a person's lifetime varies among affected individuals. Some people with Gorlin syndrome never develop any basal cell carcinomas, while others may develop thousands of these cancers. Individuals with lighter skin are more likely to develop basal cell carcinomas than are people with darker skin. Most people with Gorlin syndrome also develop noncancerous (benign) tumors of the jaw, called keratocystic odontogenic tumors. These tumors usually first appear during adolescence, and new tumors form until about age 30. Keratocystic odontogenic tumors rarely develop later in adulthood. If untreated, these tumors may cause painful facial swelling and tooth displacement. Individuals with Gorlin syndrome have a higher risk than the general population of developing other tumors. A small proportion of affected individuals develop a brain tumor called medulloblastoma during childhood. A type of benign tumor called a fibroma can occur in the heart or in a woman's ovaries. Heart (cardiac) fibromas often do not cause any symptoms, but they may obstruct blood flow or cause irregular heartbeats (arrhythmia). Ovarian fibromas are not thought to affect a woman's ability to have children (fertility). Other features of Gorlin syndrome include small depressions (pits) in the skin of the palms of the hands and soles of the feet; an unusually large head size (macrocephaly) with a prominent forehead; and skeletal abnormalities involving the spine, ribs, or skull. These signs and symptoms are typically apparent from birth or become evident in early childhood. Mutations in the PTCH1 gene cause Gorlin syndrome. This gene provides instructions for making a protein called patched-1, which functions as a receptor. Receptor proteins have specific sites into which certain other proteins, called ligands, fit like keys into locks. Together, ligands and their receptors trigger signals that affect cell development and function. A protein called Sonic Hedgehog is the ligand for the patched-1 receptor. Patched-1 blocks cell growth and division (proliferation) until Sonic Hedgehog is attached.