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Disease Profile

Attenuated familial adenomatous polyposis

Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.


US Estimated

Europe Estimated

Age of onset






Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease.


Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype.


dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.


recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder.


Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.

Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.


Not applicable


Other names (AKA)

Attenuated FAP; AFAP; Mild form of FAP;


Attenuated familial adenomatous polyposis (AFAP) is an inherited condition that increases the chance to develop cancer of the large intestine (colon) and rectum. It is a milder form of classic familial adenomatous polyposis (FAP) and is characterized by fewer colon polyps (an average of 30) and a delay in the development of colon cancer (average age 50 to 55 years). Other signs and symptoms may include benign or malignant tumors of the duodenum (a section of the small intestine) and, in rare cases, other symptoms of FAP. AFAP is caused by mutations in the APC gene and is inherited in an autosomal dominant manner. AFAP is generally managed with regular screening to detect if and when polyps develop.[1]


This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

Medical Terms Other Names
Learn More:
80%-99% of people have these symptoms
Adenomatous colonic polyposis
Colorectal polyposis
30%-79% of people have these symptoms
Colon cancer
Duodenal polyposis
Multiple gastric polyps
Neoplasm of the stomach
Stomach tumor
Rectal polyposis
5%-29% of people have these symptoms
Adenocarcinoma of the colon
Carious teeth
Dental cavities
Tooth cavities
Tooth decay

[ more ]

Congenital hypertrophy of retinal pigment epithelium
Epidermoid cyst
Skin cyst
Fibroadenoma of the breast
Increased number of teeth
Extra teeth
Increased tooth count
Supplemental teeth

[ more ]

Multiple renal cysts
Multiple kidney cysts
Thyroid adenoma
Unerupted tooth
Failure of eruption of tooth
Uterine leiomyoma
1%-4% of people have these symptoms
Adrenocortical adenoma
Desmoid tumors
Duodenal adenocarcinoma
Papillary thyroid carcinoma
Percent of people who have these symptoms is not available through HPO
Adrenocortical carcinoma
Autosomal dominant inheritance
Hyperpigmentation of the skin
Patchy darkened skin
Multiple lipomas
Multiple fatty lumps
Small intestine carcinoid
Variable expressivity


Attenuated familial adenomatous polyposis (AFAP) is generally managed with regular screening to detect if and when polyps develop.[2] Screening by colonoscopy has been recommended for affected people starting at age 20 to 25 years. People with polyps may undergo polypectomy (removal of polyps) followed by continued screenings every one to three years, depending on the number of polyps.[1] A prophylactic colectomy (removal of all or part of the colon) may be considered in people with too many adenomas to remove or those who cannot undergo screening.[3] About one third of people with AFAP have few enough colon polyps that screening with periodic polypectomy is sufficient.[1]

Because individuals with AFAP can also develop duodenal adenomas and other cancers, upper endoscopy is typically recommended starting at age 20 to 30 years and then every one to three years, depending on the number of polyps. There is currently no consensus on screening for tumors that occur outside of the colon, so it has been suggested that affected individuals are managed as if they have classic FAP.[3]

A number of drugs such as celecoxib and sulindac reportedly have been successful at reducing the number and the size of polyps in affected people, but these drugs generally help to prevent further complications and are not considered adequate treatment.[2]

Additional and more detailed information about the treatment and management of FAP, including AFAP, is available on eMedicine's Web site and can be viewed by clicking here.

Treatment of familial adenomatous polyposis (FAP) is focused on managing the risk for colon cancer. Screening for colon cancer and polyps by endoscopy may begin in childhood. There is the option to remove the colon (colectomy) before colon cancer develops. The timing of this surgery is based on multiple factors. Guidelines for treatment and management of FAP and other polyposis conditions have been developed and published.[4][5]

Specialists involved in the care of someone with familial adenomatous polyposis may include:

  • Medical geneticist
  • Gastroenterologist
  • Surgeon
  • Orthopedic surgeon
  • Ophthalmologist
  • Dentist


Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Organizations Supporting this Disease

    Organizations Providing General Support

      Learn more

      These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

      Where to Start

      • Genetics Home Reference (GHR) contains information on Attenuated familial adenomatous polyposis. This website is maintained by the National Library of Medicine.
      • The National Organization for Rare Disorders (NORD) has a report for patients and families about this condition. NORD is a patient advocacy organization for individuals with rare diseases and the organizations that serve them.

        In-Depth Information

        • GeneReviews provides current, expert-authored, peer-reviewed, full-text articles describing the application of genetic testing to the diagnosis, management, and genetic counseling of patients with specific inherited conditions.
        • Medscape Reference provides information on this topic. You may need to register to view the medical textbook, but registration is free.
        • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
        • Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
        • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
        • PubMed is a searchable database of medical literature and lists journal articles that discuss Attenuated familial adenomatous polyposis. Click on the link to view a sample search on this topic.


          1. Jasperson KW, Patel SG, Ahnen DJ. APC-Associated Polyposis Conditions. GeneReviews. Updated Feb 2, 2017; https://www.ncbi.nlm.nih.gov/books/NBK1345/.
          2. Mohammad Wehbi. Familial Adenomatous Polyposis. eMedicine. September 1, 2011; https://emedicine.medscape.com/article/175377-overview. Accessed 12/16/2011.
          3. Peter A L Bonis, MD; Dennis J Ahnen, MD; Lisen Axell, MS, CGC. Familial adenomatous polyposis and MUTYH associated polyposis: Screening and management of patients and families. UpToDate. April 2014;
          4. Provenzale D, Gupta S, Ahnen DJ, Bray T, Cannon JA, Cooper G, David DS, et al. Genetic/Familial High-Risk Assessment: Colorectal Version 1.2016, NCCN Clinical Practice Guidelines in Oncology. J Natl Compr Canc Netw. Aug 2016; 14(8):1010-30. https://pubmed.ncbi.nlm.nih.gov/27496117/.
          5. Hyer W, Cohen S, Attard T, Vila-Miravet V, Pienar C, Auth M, Septer S, et al. Management of Familial Adenomatous Polyposis in Children and Adolescents: Position Paper From the ESPGHAN Polyposis Working Group. J Pediatr Gastroenterol Nutr. Mar 2019; 68(3):428-441. https://pubmed.ncbi.nlm.nih.gov/30585891/.

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