No disease-causing mutation within the coding sequences of the hMLH1/hMSH2 and PTEN genes was found in patients with EC who had the mutator phenotype (MSI positive and IHC negative), except for a newly described hMLH1 missense mutation, Ile655Val, that was observed in 1 of 27 patients (4%).
Genetic testing for the MLH1 D132H allele exclusively is therefore unlikely to be cost effective for genetic risk assessment in American population-based and clinic-based colorectal cancer and endometrial cancer patients.