Four of the nine patients were genetically confirmed to have an inactivating/pathogenic germline mutation in one of the mismatch repair genes (three MSH2, one MSH6) in the heterozygous state with somatic tumor-acquired inactivation of the remaining allele due to either loss of heterozygosity or a second mutation present in trans (Supplementary Table S3). This evidence concerns the gene MSH6 and neoplasm.