Mutations of<i>hMLH1</i>and<i>hMSH2</i>in Patients With Suspected Hereditary Nonpolyposis Colorectal Cancer: Correlation With Microsatellite Instability and Abnormalities of Mismatch Repair Protein Expression

Abstract

No relationship was found between MMR gene mutations and MSI; low or no MSI was found in the four patients with germ-line mutations, and none of the five patients with high MSI demonstrated abnormalities of MMR genes. On the contrary, loss of hMLH1 or hMSH2 expression was found in the tumors from three of the four patients demonstrating germ-line mutations. These data suggest that germ-line mutations of the MMR gene can occur in people with MSI-negative tumors. Sensitive clinical criteria and the study of MMR gene expression may be useful to identify this subset of patients.