Although an increased CRC risk associated with bi-allelic MUTYH mutations is incontrovertible, the risk associated with one MUTYH mutant allele is controversial (Croitoru et al, 2004; Farrington et al, 2005; Jenkins et al, 2006; Tenesa et al, 2006; Webb et al, 2006; Cleary et al, 2009; Jones et al, 2009; Lubbe et al, 2009). Here, MUTYH is linked to colorectal carcinoma.