MLH1 and mismatch repair cancer syndrome 1: Despite the epigenetic silencing of the MutL protein homolog 1 (MLH1) gene that leads to MMR deficiency, frameshift mutations in the ataxia telangiectasia and Rad3-related protein, CCCTC-binding factor, Janus kinase 1, Ring finger protein 43 and ribosomal protein L22 genes have been reported in MSI(+) carcinomas.