MUTYH and colorectal carcinoma: In a study by Niessen et al. (N=210), a significantly higher frequency of carriers of monoallelic MUTYH mutations was found among CRC patients who also had a specific MMR mutation (5/36=14%), in comparison to groups of CRC patients with other MMR mutations (1/40= 2.5%) or without MMR mutations (1/134 =0.7%) [56].