The 2 main missense mutations c.1145G>A, p.Gly382Asp and c.494A>G, p.Tyr165Cys were associated with the development of colorectal adenomas/serrated polyps in these monoallelic carriers.
MAP patients carrying the p.Glu480del variant presented with a younger age at polyp diagnosis as compared to patients carrying p.Gly396Asp and p.Tyr179Cys variants.
One patient with 25 adenomas without colorectal cancer carried the c.1145G>A mutation at a homozygote state and one patient with 3 polyps was heterozygote for the mutation c.1145G>A.
Three individuals were biallelic MUTYH variant carriers (p.Y179C/p.G382D: typical MAP; p.Y179C/p.Q338H: atypical MAP with late onset and lower polyp burden; p.G382D/p.Q338H: inflammatory bowel disease), and four subjects were monoallelic mutation carriers.