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Table 1 Comparison of microsatellite-unstable colorectal cancers

From: Molecular genetics of microsatellite-unstable colorectal cancer for pathologists

  (A)
Sporadic dMMR – MLH1 Promoter Hypermethylation
(B)
Lynch Syndrome
(C)
Sporadic dMMR – Somatic MMR Mutations
(D)
Constitutional Mismatch Repair Deficiency (CMMRD)
Germline mutation None One allele of a MMR gene (MLH1, PMS2, MSH2, MSH6) None Both alleles of a MMR gene (MLH1, PMS2, MSH2, MSH6)
Somatic mutation BRAF V600E 2nd allele of the mutated MMR gene Both alleles of a MMR gene (MLH1, PMS2, MSH2, MSH6) None
Epigenetic alteration Somatic biallelic promoter methylation of MLH1 Germline deletion in 3′ end of EPCAM leads to MSH2 methylation None None
Intense Lifelong Screening No Yes No Yes
  1. Abbreviations: dMMR mismatch repair deficiency, MMR mismatch repair
  2. Adapted from Carethers and Stoffel [4]