Hereditary Nonpolypopsis Colorectal Cancer (HNPCC) is an inherited autosomal dominant genetic condition with an increased risk for colon or endometrial cancer. HNPCC is caused by a mutation in one of the genes associated with Mismatch Repair mechanism (MMR), such as MSH2. MMR repairs the single point mutations that are left uncorrected after DNA replication. This project aims to determine if a missense mutation in MSH2 affects the MMR function. The project begun with the molecular characterization of the mutation in MSH2. After plasmid purification, PCR, restriction digestion, and bioinformatic analysis, the mutation in MSH2 was determined to be H669Y. The mutated MSH2 was used to transform msh2 mutant yeast. After transformation, the mutation rate was measured with FOA assay. Our data indicated that H669Y mutation in MSH2 affected the MMR function. Data generated from this research project will allow clinics to look out for those specific alleles or mutations that put patients at risk of colorectal cancer.