MUTYH and colorectal carcinoma: Evidence of a mono-allelic MUTYH effect on CRC has been reported in several case–control studies (Croitoru et al, 2004; Wang et al, 2004; Farrington et al, 2005; Zhou et al, 2005; Tenesa et al, 2006; Cleary et al, 2009) and family-based studies (Jenkins et al, 2006; Jones et al, 2009), but not in other studies (Kambara et al, 2004; Webb et al, 2006; Balaguer et al, 2007; Lubbe et al, 2009).