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Updated: Jul 9, 2025
Quantification of Colonic Stem Cell Mutations
Published on: September 25, 2015
Monoallelic deleterious MUTYH mutations generate colorectal cancer: A case report
Bei Zhao1, Wenqi Sun1, Yunrong Wang1
1Department of Gastroenterology, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School Nanjing University Nanjing China.
Abstract:
Here we reported a particular case of MUTYH-associated polyposis (MAP) that had only one rare heterozygous variant, but some particular clinical manifestations contributed to occur in this male patient by only one defective MUTYH allele were worth of further investigation. We reported a case of MAP. It is about a 33-year-old man with chief complaints of hematochezia who had multiple polyps that were found in his colon via colonoscopy. He followed his doctor's advice and performed a genetic analysis examination. Germline test was positive for a major heterozygous variant: chr1:45800165 on the MUTYH gene. MUTYH gene sequence analysis confirmed the following heterozygous variant: c.55CT (p.R19X) in exon 2 (ClinVar NM_001128425). Unfortunately, his mother and daughter have the ILK variant according to genetic analysis. However, this variant at the site was not detected in his father. Various types of polyps were found on repeated colonoscopy, which tended to become latent cancerous in the future. This case indicated that awareness of the risk of carcinogenesis of polyps in carriers of monoallelic variants might accordingly increase, and our understanding of the type of genetically related disease will be enhanced by us.
Insights
This case highlights MUTYH-associated polyposis (MAP) in a male patient with a single heterozygous MUTYH variant. It suggests increased cancer risk awareness for monoallelic variant carriers.
Area of Science:
- Genetics
- Oncology
- Gastroenterology
Background:
- MUTYH-associated polyposis (MAP) is an autosomal recessive condition typically caused by biallelic pathogenic variants in the MUTYH gene.
- MAP is characterized by numerous colorectal adenomatous polyps and an increased risk of colorectal cancer.
Observation:
- A 33-year-old male presented with hematochezia and multiple colonic polyps.
- Genetic analysis revealed a heterozygous pathogenic variant (c.55CT, p.R19X) in the MUTYH gene.
- The patient's mother and daughter carried an ILK variant, but not the identified MUTYH variant.
Findings:
- The patient exhibited clinical manifestations of MAP despite having only one defective MUTYH allele (monoallelic variant).
- Colonoscopies revealed various polyp types with a tendency towards future cancerous transformation.
- The identified heterozygous variant was chr1:45800165 on the MUTYH gene, confirmed via sequencing.
Implications:
- This case underscores the potential for significant clinical manifestations in individuals with monoallelic MUTYH variants.
- Increased awareness of polyp carcinogenesis risk in monoallelic variant carriers is warranted.
- Further investigation into the genetic and clinical correlations of monoallelic MUTYH variants may enhance understanding of genetically related diseases.
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