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[Homozygous germline mutation in MUTYH gene in familial adenomatous polyposis]
Karin Alvarez1, Marjorie de la Fuente, Paulina Orellana
1Laboratorio de Oncología y Genética Molecular, Unidad de Coloproctología, Clínica Las Condes, Santiago, Chile.
Abstract:
Recently, MUTYH mutations have been reported to predispose to the development of polyposis. However, polyposis caused by mutations in MUTYH has been characterized as an autosomal recessive hereditary disease, different from the autosomal dominant pattern observed in polyposis caused by APC mutations. We report a 41-year-old female consulting for anemia. Colonoscopy detected multiple sessile polyps and a cecal carcinoma. The patient was operated and in the surgical piece, the tumor invaded serosa and there was lymph node involvement. Approximately 100 polyps were found. The patient received 5-fluorouracil, as adjuvant therapy. The patient had a sister (of a total of 12 brothers) with a colorectal carcinoma. The genetic study identified a homozygous mutation of the MUTYH gene, called c.340T > C, that produces an amino acid change of tyrosine for histidine called p.Y114H. The sister with colorectal cancer was a heterozygous carrier of this mutation.
Insights
Mutations in the MUTYH gene can cause hereditary polyposis. This study identifies a specific homozygous MUTYH mutation (p.Y114H) in a patient with colorectal cancer and polyposis, highlighting its role in autosomal recessive inheritance.
Area of Science:
- Genetics
- Oncology
- Gastroenterology
Background:
- Mutations in the MUTYH gene are associated with colorectal polyposis.
- MUTYH-associated polyposis typically follows an autosomal recessive inheritance pattern, distinct from APC mutations (autosomal dominant).
Observation:
- A 41-year-old female presented with anemia and was found to have multiple colonic polyps and a cecal carcinoma.
- The patient underwent surgery for the carcinoma, which showed serosal invasion and lymph node involvement.
- Approximately 100 polyps were identified in the colon.
Findings:
- Genetic analysis revealed a homozygous c.340T > C mutation in the MUTYH gene (p.Y114H).
- The patient's sister, who had colorectal cancer, was a heterozygous carrier of the same mutation.
- This homozygous mutation was linked to the patient's presentation of polyposis and colorectal cancer.
Implications:
- This case reinforces the role of homozygous MUTYH mutations in the development of hereditary colorectal polyposis and cancer.
- Understanding the specific genetic mutations, like p.Y114H, is crucial for accurate diagnosis and genetic counseling.
- Further research into MUTYH-associated polyposis can improve early detection and management strategies for affected families.
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