MUTYH

Familial adenomatous polyposis

Mutations in the MUTYH gene cause an autosomal recessive form of familial adenomatous polyposis (also called MUTYH-associated polyposis). Mutations in this gene affect the ability of cells to correct errors made during DNA replication. In individuals who have autosomal recessive familial adenomatous polyposis, both copies of the MUTYH gene in each cell are mutated. Most mutations in this gene result in the production of a nonfunctional or low-functioning MYH glycosylase. When base excision repair in the cell is impaired, mutations in other genes build up, leading to cell overgrowth and possibly tumor formation. Two mutations that change the sequence of the building blocks of proteins (amino acids) in MYH glycosylase are common in people of European descent. One mutation replaces the amino acid tyrosine with the amino acid cysteine at position 179 (written as Tyr179Cys or Y179C). The other mutation switches the amino acid glycine with the amino acid aspartic acid at position 396 (written as Gly396Asp or G396D).