The MUTYH gene is involved in oxidative DNA damage repair. Mutations in this gene affect the ability of cells to correct mistakes made during DNA replication. Both copies of the MUTYH gene are mutated in individuals who have MUTYH associated polyposis (MAP). It is an autosomal recessive form of familial adenomatous polyposis (FAP2). Most reported mutations in this gene cause production of a nonfunctional or low functioning glycosylase enzyme. When base repair in the cell is compromised, mutations in other genes build up, leading to cell overgrowth and possibly tumor formation.
It can be difficult to distinguish this recessive form of polyposis from that of autosomal dominant familial adenomatous polyposis (FAP1) caused by mutations in APC gene. The number of adenomas is often lower in MAP (from 5 to more than 100), and affected patients are often sporadic cases. MUTYH mutations have also been detected in patients affected with early-onset colorectal cancer (CRC) with and without polyps. Cancers are more frequently located in the proximal side of the colon compared to APC-related FAP1. Generally, mean age at diagnosis of MAP is 48-56 years, later than in APC-related FAP1. A number of extracolonic conditions have been observed, although their incidence is not yet well established. These include symptoms that are also associated with APC-related FAP1, such as duodenal polyposis, duodenal cancer, osteomas, dental cysts and congenital hypertrophy of the retinal pigment epithelium. Breast cancer and thyroid cancer, and cutaneous tumors have also been reported
Methodology: Sequencing of entire coding region
Purpose: Confirmation of Clinical Diagnosis/Carrier Testing
Test Requisition: Sequencing Requisition
CPT Code: 81406 Cost: $869.00
Turn-around-time: 3-4 weeks
1. Parker, A; Gu Y, Mahoney W, Lee S H, Singh K K, Lu A L (2001). "Human homolog of the MutY repair protein (hMYH) physically interacts with proteins involved in long patch DNA base excision repair". J. Biol. Chem. 276 (8): 5547–55.
2. Sieber, O. M., Lipton, L., Crabtree, M., Heinimann, K., Fidalgo, P., Phillips, R. K. S., Bisgaard, M.-L., Orntoft, T. F., Aaltonen, L. A., Hodgson, S. V., Thomas, H. J. W., Tomlinson, I. P. M (2003). “Multiple colorectal adenomas, classic adenomatous polyposis, and germ-line mutations in MYH”. New Eng. J. Med. 348: 791-799.