As shown in Fig. 1D, PCDH18 hypermethylation was frequent in primary CRC tissues (25/29, 86.2%), and there were statistically significant differences in the methylation status of PCDH18 between CRC tissues (median, 15.17%, range, 0.0285–100%) and normal controls (median, 0.4438%, range, 0.0–3.712%)(Table 1). Here, PCDH18 is linked to colorectal carcinoma.