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Molecular Genetics of MUTYH-Associated Polyposis

  1. Maartje Nielsen1,
  2. Stefan Aretz2,
  3. Julian R Sampson3

Published Online: 15 MAR 2013

DOI: 10.1002/9780470015902.a0024293

eLS

eLS

How to Cite

Nielsen, M., Aretz, S. and Sampson, J. R. 2013. Molecular Genetics of MUTYH-Associated Polyposis. eLS. .

Author Information

  1. 1

    Leiden University Medical Centre, Leiden, The Netherlands

  2. 2

    University of Bonn, Bonn, Germany

  3. 3

    Cardiff University, Cardiff, UK

Publication History

  1. Published Online: 15 MAR 2013

Abstract

MUTYH-associated polyposis (MAP) is an autosomal recessive condition characterised by the development of multiple colon polyps and colorectal cancer (CRC). It is caused by biallelic germline mutations in the human mutY homologue (MUTYH) gene on 1p34.3. The MUTYH protein is a base excision repair glycosylase involved in the repair of oxidation of a guanine leading to 8-oxo-7,8-dihydro-2′-deoxyguanosine. MUTYH recognises an oxoG:A mismatch and excises the undamaged adenine base using a base-flipping mechanism.

Most carriers of biallelic MUTYH mutations develop between 10 and 500, predominantly adenomatous polyps and CRC, but a number of MAP patients have CRC without polyps. The lifetime CRC risk in MAP patients is between 40% and 100% in the absence of timely surveillance. The lifetime risk for duodenal cancer is approximately 4% and a modest, but significant increase in incidence has been shown for ovarian, bladder and skin cancer.

Key Concepts:

  • MUTYH-associated polyposis (MAP) is an autosomal recessive inherited polyposis and CRC syndrome.

  • MAP is caused by mutations in both alleles of the MUTYH gene.

  • One of the key functions of the MUTYH protein is prevention of mutagenesis caused by oxidative DNA damage of guanine.

  • Loss of MUTYH activity leads to somatic G>T transversions.

  • In the North West (NW) European population, two founder missense mutations, the p.G396D and p.Y179C, compromise more than 90% of mutations reported.

  • A somatic hotspot KRAS2 mutation in codon 12 (c.34 G>T) is present in about half of MAP-associated colon tumours.

Keywords:

  • MUTYH-associated polyposis;
  • MUTYH gene;
  • MAP;
  • colorectal cancer;
  • polyposis