Familial adenomatous polyposis (FAP)

This is an autosomal dominant condition with a high degree of penetrance. It is caused by a mutation of the apc gene.

Pathological features:

• Multiple adenomatous polyps develop in the colon, usually between the ages 13-30yrs
• Progression through the polyp-cancer sequence is inevitable

Clinical features:

• The condition is initially asymptomatic, although a family hx may be present
• Blood from the rectum is the most common symptom
• Tenesmus
• Diarrhoea

Dx and Mx:

• Dx is made by endoscopy
• Siblings should be examined
• Total colectomy is essential because of the universal progression to cancer
• An ileoanal reconstruction is usually possible