MLH1 and neoplasm: Constitutional secondary epimutations with cis effect have been described in several loci, but particularly in tumor suppressor genes including FMR1, SNURF/SNRPN, HBA2, H19, LIT1, MSH2, DAPK1, MLH1, CDH1, MGMT, MMACHC, and BRCA1. During the 1990s, the first reports were focused on promoter cis-acting epimutations.