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Findings that shed new light on the possible pathogenesis of a disease or an adverse effect
Case report
Attenuated familial adenomatous polyposis (AFAP) in a patient associated with a novel mutation in APC
  1. Vivek Sant1,
  2. Elsa Reich2,
  3. Lauren Khanna3,
  4. Wenqing Cao4,
  5. Susan Kornacki4 and
  6. Alexis Grucela1
  1. 1 Division of Colon and Rectal Surgery, Department of Surgery, New York University School of Medicine, New York City, New York, USA
  2. 2 Department of Pediatrics, Genetic Counseling, New York University School of Medicine, New York City, New York, USA
  3. 3 Division of Gastroenterology, New York University School of Medicine, New York City, New York, USA
  4. 4 Department of Pathology, New York University School of Medicine, New York City, New York, USA
  1. Correspondence to Dr Vivek Sant; Vivek.Sant{at}nyulangone.org

Abstract

Familial adenomatous polyposis (FAP) is an autosomal dominant syndrome associated with mutation in the adenomatous polyposis coli (APC) gene, a tumour suppressor located on chromosome 5q21. Attenuated familial adenomatous polyposis (AFAP) is a variant associated with fewer and later onset of colon polyps. AFAP-associated APC mutations have largely been found before codon 157, in exon 9 or after codon 1595. We present the case of a 44-year-old man incidentally found to have numerous gastric polyps during bariatric surgery, with innumerable polyps in the remaining part of the stomach and the entire colon, with rectal sparing, consistent with AFAP phenotype. Genetic testing demonstrated the c.7682dup (p.Ser2562Lysfs*21) variant in exon 15 of APC. This represents a previously undescribed APC mutation. This mutation likely yields end-binding protein 1 and human disc large binding protein inactivation, causing cell cycle microtubule dysregulation and tumour suppressor inactivation. Through loss of these regulatory mechanisms, this mutation is associated with AFAP phenotype. The patient was treated surgically and is doing well.

  • general surgery
  • endoscopy
  • genetic screening / counselling
  • colon cancer
  • surgical oncology

https://doi.org/10.1136/bcr-2019-231232

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    Footnotes

    • Contributors VS, AG, ER, LK, WC, SK were involved clinically with the patient in question. VS, AG, ER, LK, WC, SK all contributed to writing this manuscript.

    • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

    • Competing interests None declared.

    • Patient consent for publication Obtained.

    • Provenance and peer review Not commissioned; externally peer reviewed.