For example, 3 of the mutation carriers identified in the retrospective OSU studies had tumours that were MSI-L or MSS: all 3 of these patients had MSH6 mutations.2,3 De Leeuw et al. found that tumours from 12 MSH6 mutation carriers showed a low level of MSI across a panel of 30-40 markers. This evidence concerns the gene MSH6 and neoplasm.