As expected, we found that the methylation density of CpG site-27/31/36/37/42/43 within the sequenced p16 fragment in the H. pylori-positive normal/gastritis samples (N = 13) was statistically significantly higher than that in the H. pylori-negative ones (N = 7), especially in the exon-1 coding-nucleosomal region (Wann Whitney test, P≤0.040; Table 1 and Figure 5B). Here, CDKN2A is linked to gastritis.