| Familial Adenomatous Polyposis |
| Geno
|
Mag
|
Summary
|
| (C;C)
|
0
|
common/normal
|
| (C;T)
|
6.5
|
Familial Adenomatous Polyposis
|
| (T;T)
|
3
|
risk factor for colorectal cancer?
|
This is a genotype with recommended actions if clinically confirmed. In brief:
- Classic Familial Adenomatous Polyposis (FAP) is characterized by the presence of ≥100 adenomatous polyps. About 10% of cases are referred to as attenuated FAP (AFAP) and have milder disease progression.
- Treatment for FAP should include thorough counseling about the nature of the syndrome and the need for compliance with recommendations for management and surveillance.
- Annual endoscopic surveillance (i.e., flexible sigmoidoscopy or colonoscopy) is recommended until the polyp burden necessitates that colectomy is performed.
- Colonscopic clearance of adenomas in patients with classical FAP cannot guarantee that cancer will be prevented; therefore, removal of the at-risk epithelium ((procto)colectomy) is considered the standard of care.
- Surveillance for gastric and proximal small bowel tumors with esophagogastroduodenoscopy using forward and side-viewing endoscopes should begin at age 20 to 30.
- The increased relative risks relative to average population risks for various cancers for classic FAP are about 800-1000x higher for desmoid tumors, 100-300x for duodenal cancer, ~5x for pancreatic cancer, and 2-4 for adrenal masses.
The full ClinGen Actionability report about Familial Adenomatous Polyposis (FAP) can be found here.
Genetic counseling may be available to you through your health-care network. In the US, genetic counselors may be found via this webpage of the National Society of Genetic Counselors.
