First AD

Second AD

A 25-year-old woman undergoes a screening colonoscopy, recommended because of a family history of colon cancer. She is noted to have multiple polyps throughout her colon, all of which are adenomas. She has a history of an acute abdomen secondary to a desmoid tumor and a mandibular osteoma diagnosed as a child.

This patient has Gardner syndrome, an autosomal dominant familial disease consisting of multiple adenomatous polyps and osteomas. This condition is related to the familial adenomatous polyposis (FAP) syndrome and is secondary to a defect in the APC gene. Other extracolonic associated findings include desmoids tumors, thyroid cancer, and sebaceous cysts. The PTEN gene is associated with Cowden syndrome; MYP gene with Lynch syndrome; and STK11 with Peutz-Jeghers syndrome.

Gastrointestinal Disorders

A young woman with a history of a desmoid tumor as a child undergoes a screening colonoscopy. What gene mutation is suggested by the finding of multiple adenomatous polyps?

Bad Genes, But Which Ones?