Turcot syndrome is a genetic condition that causes the formation of non-cancerous (benign) growths (polyps) to form in the body. These polyps can become cancerous over time if left untreated. In addition to the polyps, which usually develop in the colon, people with Turcot syndrome are also at risk for cancerous tumors in the brain. The two most common types of brain cancer in Turcot syndrome are tumors found in the back of the brain (medulloblastomas) and tumors found in the brain and spine (glioblastomas). Turcot syndrome is similar to two other genetic conditions that also increase the risk for colon polyps and brain cancer: Lynch syndrome, which can also cause glioblastomas, and familial adenomatous polyposis (FAP), which can also increase the risk of medulloblastomas.
Turcot syndrome is caused by changes (mutations) in genes that are important in the repair of DNA damage, called mismatch repair genes. Turcot syndrome that is similar to Lynch syndrome is caused by mutations in the MLH1 and PMS2 genes. Turcot syndrome that is similar to FAP is caused by a mutation in the APC gene. No matter which gene has the mutation, all forms of Turcot syndrome are inherited in an autosomal dominant way, meaning a mutation in only one of the two gene copies a person has is enough to cause the condition.
The diagnosis of Turcot syndrome is considered in a person with numerous colon polyps along with one of the brain related cancers listed above. Genetic testing is used to confirm the diagnosis. Treatment depends on the type of cancer a person has, but usually includes removal of polyps before they become cancerous. If your child has been diagnosed with Turcot syndrome, talk to their doctor about a plan to identify polyps and cancer at an early stage. Meeting with a genetic counselor may be helpful to determine who else in the family is at risk for the condition. Support groups can provide additional information.