For example, hypermethylation of OGG1 genes was observed in thyroid cancer [49], MLH1 gene in oral squamous cell carcinoma [50], neck squamous cell carcinoma [51], non-small cell lung cancer (NSCLC) [52], acute myeloid leukemia (AML) [53], gastric cancer [54], ovarian cancer [55], and BRCA1 gene in breast cancer [56], bladder cancer [57], NSCLC [58], and gastric cancer [59]. The gene discussed is BRCA1; the disease is gastric cancer.