MUTYH Monoallelic gene - Cancer risk, management, and testing for genetic mutations

Associated Syndrome Name: Carrier Status for MUTYH-associated polyposis syndrome (MAP)

MUTYH Monoallelic gene Overview

Carrier Status for MUTYH-associated polyposis syndrome (MAP) 1, 2, 3, 4, 5
  • Some studies have shown that individuals with a single MUTYH mutation (monoallelic MUTYH) may have a small increased risk for colorectal cancer compared to individuals in the general population. However, other studies have found no significantly increased risk for colorectal cancer. Given the conflicting data, there are currently no specialized colorectal cancer screening recommendations based on having a single MUTYH mutation (monoallelic MUTYH).
  • Individuals with mutations in both of their copies of the MUTYH gene (biallelic mutations) have a condition known as MUTYH-associated polyposis (MAP), which is associated with a high risk for cancer. This patient does not have a diagnosis of MAP, but may have relatives who are at risk for this condition. Please see the Information for Family Members section below for details.

Benefits of Testing for MUTYH Monoallelic Gene Mutations:

Testing for MUTYH Monoallelic gene mutations with the MyRisk® Hereditary Cancer Test with RiskScore® provides critical insights to patients and providers about potential hereditary cancer risk. Identifying a MUTYH Monoallelic gene mutation can help clarify whether a patient is at increased risk for certain cancers and guide proactive, personalized care planning. With definitive answers from the MyRisk Test, healthcare providers can better tailor screening, prevention, and management strategies, while patients gain clarity and confidence about their hereditary cancer risk. In addition, understanding a MUTYH Monoallelic gene mutation allows family members to consider their own hereditary cancer risk, supporting informed decision-making and potentially life-saving early interventions. Learn more about the MyRisk® with RiskScore® Hereditary Cancer Test.

Information for Family Members

The following information for Family Members will appear as part of the MMT for a patient found to have a mutation in the MUTYH Monoallelic gene.

This patient's relatives are at risk for carrying the same mutation(s) and associated cancer risks as this patient. Cancer risks for females and males who have this/these mutation(s) are provided below.

Family members should talk to a healthcare provider about genetic testing. Close relatives such as parents, children, brothers and sisters have the highest chance of having the same mutation(s) as this patient. Other more distant relatives such as cousins, aunts, uncles, and grandparents also have a chance of carrying the same mutation(s). Testing of at-risk relatives can identify those family members with the same mutation(s) who may benefit from surveillance and early intervention.

This patient carries a single MUTYH mutation (monoallelic). This patient's relatives are at risk for carrying a single MUTYH mutation, or mutations in both copies of MUTYH (biallelic). Relatives who have inherited mutations in both copies of MUTYH are at risk for MUTYH-associated polyposis syndrome (MAP), with a 43%-100% risk of colorectal cancer risk to age 80 and a 5% risk for small bowel cancer. Genetic testing may be appropriate for close family members to determine whether they are at an increased risk for colorectal and other cancers.

References

  1. Jones N, et al. Increased colorectal cancer incidence in obligate carriers of heterozygous mutations in MUTYH. Gastroenterology. 2009 137:489-94 PubMed PMID: 19394335.
  2. Win AK, et al. Risk of colorectal cancer for carriers of mutations in MUTYH, with and without a family history of cancer. Gastroenterology. 2014 146:1208-11. PMID: 24444654.
  3. Nielsen M, et al. MUTYH Polyposis. 2021 May 27. In: Pagon RA, et al., editors. GeneReviews® [Internet]. PMID: 23035301.
  4. Jenkins MA, et al. Risk of colorectal cancer in monoallelic and biallelic carriers of MYH mutations: a population-based case-family study. Cancer Epidemiol Biomarkers Prev. 2006 15:312-4. PMID: 16492921.
  5. Thompson AB, et al. Monoallelic MUTYH pathogenic variants ascertained via multi-gene hereditary cancer panels are not associated with colorectal, endometrial, or breast cancer. Fam Cancer. 2022 Oct;21(4):415-422. PMID: 34981295.
Last Updated on 15-Sep-2025