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Familial adenomatous polyposis 1

Synonyms
APC-Associated Polyposis Conditions; Colon Cancer (APC I1307K related); FAMILIAL ADENOMATOUS POLYPOSIS 1, ATTENUATED; POLYPOSIS, ADENOMATOUS INTESTINAL

Summary

Excerpted from the GeneReview: APC-Associated Polyposis Conditions
APC-associated polyposis conditions include (classic or attenuated) familial adenomatous polyposis (FAP) and gastric adenocarcinoma and proximal polyposis of the stomach (GAPPS). FAP is a colorectal cancer (CRC) predisposition syndrome that can manifest in either classic or attenuated form. Classic FAP is characterized by hundreds to thousands of adenomatous colonic polyps, beginning on average at age 16 years (range 7-36 years). For those with the classic form of FAP, 95% of individuals have polyps by age 35 years; CRC is inevitable without colectomy. The mean age of CRC diagnosis in untreated individuals is 39 years (range 34-43 years). The attenuated form is characterized by multiple colonic polyps (average of 30), more proximally located polyps, and a diagnosis of CRC at a later age than in classic FAP. For those with an attenuated form, there is a 70% lifetime risk of CRC and the mean age of diagnosis is 50-55 years. Extracolonic manifestations are variably present and include polyps of the stomach and duodenum, osteomas, dental abnormalities, congenital hypertrophy of the retinal pigment epithelium (CHRPE), benign cutaneous lesions, desmoid tumors, adrenal masses, and other associated cancers. GAPPS is characterized by proximal gastric polyposis, increased risk of gastric adenocarcinoma, and no duodenal or colonic involvement in most individuals reported.
Full text of GeneReview (by section):
Summary
GeneReview Scope
Diagnosis
Clinical Characteristics
Genetically Related (Allelic) Disorders
Differential Diagnosis
Management
Genetic Counseling
Resources
Molecular Genetics
Chapter Notes
References
Authors:
Timothy Yen
Peter P Stanich
Lisen Axell
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Available tests

134 tests are in the database for this condition.

Clinical tests (134 available)

Biochemical Genetics Tests

Molecular Genetics Tests

Genes See tests for all associated and related genes

  • Also known as: BTPS2, DESMD, DP2, DP2.5, DP3, GS, PPP1R46, APC
    Summary: APC regulator of WNT signaling pathway

Clinical features

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Imported from Human Phenotype Ontology (HPO)

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Reviews

Suggested reading

Clinical resources

Practice guidelines

  • NCCN, 2024
    NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines®) Colon Cancer, 2024
  • ACMG ACT, 2019
    American College of Medical Genetics and Genomics, Genomic Testing (Secondary Findings) ACT Sheet, APC Pathogenic Variants (Familial Adenomatous Polyposis [FAP]), 2019
  • ACMG ACT, 2012
    American College of Medical Genetics and Genomics Family History ACT Sheet, Colon Cancer (Asymptomatic), 2012
  • EuroGenetest, 2011
    Clinical utility gene card for: familial adenomatous polyposis (FAP) and attenuated FAP (AFAP).

Molecular resources

Consumer resources

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