Colorectal cancer in a monoallelic MYH mutation carrier.

Although the literature describes mutY homolog gene (MYH) polyposis as an autosomal recessive syndrome, we report a case of colorectal cancer in a carrier of MYH polyposis. Biallelic mutations in the MYH gene have been shown to increase the risk of colorectal cancer over the lifetime of the mutation carrier.1,2 However, there is no clear consensus in the literature as whether a monoallelic mutation increases the risk for colorectal cancer.3 In this report, we postulate that a single mutation is sufficient to increase the risk of colorectal cancer. We also propose that the G382D MYH mutation may play a dominant rather than a recessive role in polyposis and cancer development.