Moreover, we showed that the low methylation levels of cg sites (cg02269161, cg03226737, cg08185661, cg18560328, cg22723056, and cg24678137) of SYT9 were correlated with an unfavorable OS (P = 0.004, P = 0.014, P = 0.037, P = 0.001, P = 0.005, and P = 0.007, respectively) (Figure 6(a–e) and 6(f)), whereas other methylation cg sites (cg08913010, cg14243481, cg16437728, and cg26945996) did not have a prognostic value for GC patients (P = 0.926, P = 0.065, P = 0.059, and P = 0.056, respectively) (Figure S6D, S6E, S6F and S6G). The gene discussed is SYT9; the disease is gastric cancer.