Attenuated familial adenomatous polyposis
Type of disease: Rare conditions
Attenuated adenomatous familial polyposis (AFAP) is a specific form of familial adenomatous polyposis (FAP), a genetic condition that causes growths (polyps) in the large intestine (colon) and rectum that become cancerous over time. AFAP is considered to be a milder form of FAP. Individuals with AFAP tend to have a lesser amount of polyps, as well as a later age of onset, compared to those with FAP. Persons with AFAP usually have less than 100 polyps and develop colon cancer in their 50s, whereas individuals with FAP can have hundreds to thousands of polyps and tend to develop colon cancer in their 30s or 40s. Individuals with AFAP are also less likely to develop tumors in other areas of the body, unlike those affected by FAP.
Both FAP and AFAP are caused by a change (mutation) in the APC gene. This gene helps to keep cell growth under control. Mutations in APC can cause uncontrolled cell growth, leading to polyp formation in the colon and rectum. AFAP is inherited in an autosomal dominant manner, which means a mutation in only one of the two copies a person has is enough to cause the condition.
Diagnosis of AFAP is considered in a person with multiple polyps in their colon that are identified with a procedure that uses a camera inserted into the colon (colonoscopy). The diagnosis is confirmed with genetic testing. Treatment of AFAP typically consists of regular colonoscopies to find and remove polyps before they become cancerous. In some cases, removal of part of the colon may be needed. If you or your child has been diagnosed with AFAP, talk to a doctor about the right treatment options. Meeting with a genetic counselor may also be helpful to discuss the inheritance of AFAP in your family. Additional resources, such as support groups, can also be helpful.