In yeast and human colon cancer cells, loss of MutSβ secondary to MSH3 inactivation results in MSI of dinucleotide repeats (usually as low MSI) and MSI of tetranucleotide repeats (EMAST) with no apparent effect on mononucleotide repeats [30–32] which is consistent with the findings in adenoma-derived DNA of the MSH3-related polyposis patients [11]. The gene discussed is MSH3; the disease is polyposis.