Smith et al. [134] analyzed the methylation status of several genes—APC, CDKN2A, ID4, MGMT, RBP1, RUNX3, SFRP1, TIMP3, and TMEFF2—in esophageal adenocarcinoma (EAC), high-grade dysplastic BE, and metaplastic BE from patients without dysplasia or adenocarcinoma, as well as in histologically normal esophageal squamous epithelium. The gene discussed is ID4; the disease is Barrett esophagus.