PCDH11X and colorectal carcinoma: We think that this isolated increase in mutation rate is likely a consequence of LOH on chromosome 18 in tumors isolated from Apcmin/+ mice for the following reasons: (i) the pattern was not seen in the whole-genome sequencing data (Fig. 2D), (ii) the pattern was not seen in tumors isolated from Apcmin/+Msh2fl/flVC mice in which LOH on chromosome 18 was not observed, and (iii) the mutated genes on chromosome 18 are almost exclusively found in a cluster of protocadherin genes and predicted genes expressed primarily in the brain (47) and thus presumably unrelated to CRC.