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GTR Home > Tests > Variant Resolution Test for CancerNext® (+RNAinsight®)


This is a clinical test intended for Help: Diagnosis, Pre-symptomatic

Clinical summary


Imported from GeneReviews

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.

Clinical features


Imported from Human Phenotype Ontology (HPO)

  • Astrocytoma
  • Carcinoma
  • Colon cancer
  • Carious teeth
  • Epidermoid cysts
  • Fibroma
  • Keloid
  • Medulloblastoma
  • Odontoma
  • Osteoma
  • Teeth, supernumerary
  • Eruption failure
  • Desmoid tumor
  • Hyperpigmentation of the skin
  • Fibroadenoma of the breast
  • Hepatoblastoma
  • Adrenocortical adenoma
  • Adrenal cortex carcinoma
  • Gastric polyposis
  • Papillary thyroid carcinoma
  • Duodenal adenocarcinoma
  • Congenital hypertrophy of retinal pigment epithelium
  • Duodenal polyposis
  • Multiple lipomas
  • Adenomatous colonic polyposis
  • Small intestine carcinoid
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Conditions tested

Target population


Not provided

Clinical validity


Clinical validity depends on specific clinical and family history.


Not provided

Clinical utility


Not provided

Suggested reading

Practice guidelines

  • NCCN, 2023
    NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines®) Colon Cancer, 2023
  • 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).

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