MBD4 and colorectal carcinoma: However, there has been a report of a monoallelic carrier of an MBD4 pathogenic variant that developed ~ 30 adenomatous polyps and a CRC at 42 years of age with loss of MDB4 protein expression, LOH of the wildtype MBD4 allele and an enrichment of C>T transitions within CpG sites within the CRC tissue, consistent with biallelic inactivation of MBD4 via a somatic second hit [97].