SLC6A3 and bulimia nervosa: In this regard, Frieling et al. observed elevated methylation levels at the promoter region of the atrial natriuretic peptide in patients with Bulimia Nervosa (BN) [18], hypermethylation of the dopamine transporter (DAT) promoter region in BN, and hypermethylation of the dopamine D2 receptor (DRD2) promoter in AN patients [19].