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Disease Profile

Familial adenomatous polyposis

Prevalence
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.
1-9 / 100 000

3,310 - 29,790

US Estimated

1-9 / 100 000

5,135 - 46,215

Europe Estimated

Age of onset

Adult

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ICD-10

D12.6

Inheritance

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

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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

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X-linked
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.

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

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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.

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Not applicable

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Other names (AKA)

Adenomatous polyposis coli; FAP; Familial adenomatous polyposis of the colon;

Categories

Hereditary Cancer Syndromes; Rare Cancers

Summary

Familial adenomatous polyposis (FAP) leads to the growth of hundreds to thousands of non-cancerous (benign) polyps in the colon and rectum. Overtime, the polyps can become cancerous (malignant), leading to colorectal cancer at an average age of 39 years. Symptoms of FAP may include dental abnormalities, tumors of the connective tissue (desmoid tumors), and benign and malignant tumors of the duodenum (a section of the small intestine), liver, bones, skin, and other tissues. Attenuated familial adenomatous polyposis (AFAP) is a milder form of FAP which includes fewer colon polyps (an average of 30). People with AFAP have an increased risk of developing colon cancer at a later age than classic FAP. FAP is due to genetic variants in the APC gene and is inherited in an autosomal dominant pattern. FAP is diagnosed based on the symptoms, clinical examination, and may be confirmed by the results of genetic testing. Management for FAP includes regular colon screening with endoscopy and other methods. Total removal of the colon (colectomy) is usually recommended to substantially reduce the risk for colon cancer. The recommended timing of surgery is based on multiple factors.[1][2][3][4]

Symptoms

The following list includes the most common signs and symptoms in people with familial adenomatous polyposis (FAP). These features may be different from person to person, even within the same family. Some people may have more symptoms than others, and they can range from mild to severe. This list does not include every symptom that has been described in the condition.

Symptoms may include:[1][2][3]

  • Hundreds to thousands of noncancerous growths (benign polyps) in the colon
  • Colon cancer
  • Polyps of the stomach
  • Adenomatous polyps of the small intestines
  • Benign bone tumors (osteomas)
  • Dental abnormalities
  • A pigmented spot within the outer layer of the retina (Congenital hypertrophy of the retinal pigment epithelium-CHRPE)
  • Benign skin abnormalities
  • Desmoid tumors
  • Other types of cancer (small bowel, stomach, pancreas, thyroid, central nervous system, liver, bile ducts, and/or adrenal gland)

Congenital hypertrophy of the retinal pigment epithelium (CHRPE) may be present at birth, but can only be seen with an eye exam. Colon polyps usually appear in the teens, and left untreated, most people with FAP will develop colon cancer by their late 30s or early 40s.

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:
HPO ID
80%-99% of people have these symptoms
Adenomatous colonic polyposis
0005227
Duodenal polyposis
0004783
Multiple gastric polyps
0004394
30%-79% of people have these symptoms
Colon cancer
0003003
5%-29% of people have these symptoms
Carious teeth
Dental cavities
Tooth cavities
Tooth decay

[ more ]

0000670
Congenital hypertrophy of retinal pigment epithelium
0007649
Delayed eruption of teeth
Delayed eruption
Delayed teeth eruption
Delayed tooth eruption
Eruption, delayed
Late eruption of teeth
Late tooth eruption

[ more ]

0000684
Epidermoid cyst
Skin cyst
0200040
Fibroadenoma of the breast
0010619
Fibroma
0010614
Increased number of teeth
Extra teeth
Increased tooth count
Supplemental teeth

[ more ]

0011069
Irregular hyperpigmentation
0007400
Multiple lipomas
Multiple fatty lumps
0001012
Neoplasm of the central nervous system
Tumors of the central nervous system
0100006
Odontoma
0011068
Osteoma
0100246
Unerupted tooth
Failure of eruption of tooth
0000706
1%-4% of people have these symptoms
Adrenocortical adenoma
0008256
Desmoid tumors
0100245
Duodenal adenocarcinoma
0006771
Hepatoblastoma
0002884
Medulloblastoma
0002885
Papillary thyroid carcinoma
0002895
Percent of people who have these symptoms is not available through HPO
Adrenocortical carcinoma
0006744
Astrocytoma
0009592
Autosomal dominant inheritance
0000006
Carcinoma
0030731
Hyperpigmentation of the skin
Patchy darkened skin
0000953
Keloids
0010562
Small intestine carcinoid
0006722
Variable expressivity
0003828

Cause

Familial adenomatous polyposis occurs when the APC gene is not working correctly. DNA changes known as pathogenic variants are responsible for making genes work incorrectly or sometimes, not at all.[1]

Diagnosis

Familial adenomatous polyposis (FAP) is diagnosed based on the symptoms, clinical examination, and may be confirmed by the results of genetic testing. Imaging studies of the colon by endoscopy such as flexible sigmoidoscopy, colonoscopy, or other methods may also be helpful. Prenatal testing and genetic testing for at-risk relatives are possible if the disease-causing mutation in the family is known. Because colon screening for those at risk for classic FAP begins as early as age ten years, genetic testing is generally offered to children by this age. Testing may be offered earlier if the child is showing signs or symptoms of FAP.[1]

The Genetic Testing Registry (GTR) is a centralized online resource for information about genetic tests. The intended audience for the GTR is health care providers and researchers. Patients and consumers with specific questions about a genetic test should contact a health care provider or a genetics professional.

Treatment

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

Organizations

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

      • MedlinePlus Genetics contains information on Familial adenomatous polyposis. This website is maintained by the National Library of Medicine.
      • The Merck Manual provides information on this condition for patients and caregivers.
      • The National Cancer Institute provides the most current information on cancer for patients, health professionals, and the general public.
      • 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 Merck Manual for health care professionals provides information on Familial adenomatous polyposis.
        • 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 Familial adenomatous polyposis. Click on the link to view a sample search on this topic.

          References

          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. Dinarvand P, Davaro EP, Doan JV, Ising ME, Evans NR, Phillips NJ, Lai J, Guzman MA. Familial Adenomatous Polyposis Syndrome: An Update and Review of Extraintestinal Manifestations.. Arch Pathol Lab Med. Nov 2019; 143(11):1382-1398. https://pubmed.ncbi.nlm.nih.gov/31070935/.
          3. Carr S, Kasi A.. Familial Adenomatous Polyposis. StatPearls. Nov 24, 2020; https://pubmed.ncbi.nlm.nih.gov/30855821/.
          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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