AUD-associated blood DNA methylation changes around transcription start sites or promoter regions of 12 candidate genes (ANP, AVP, GDAP1, GRIN2B, HERP, MAOA, OPRM1, Orexin A, POMC, SLC6A3, SLC6A4, and SNCA) have been examined in 14 published studies (Table 2). These genes exert effects on a variety of cellular functions, such as thirst and sodium balance (AVP [coding for arginine vasopressin] and ANP [coding for atrial natriuretic peptide]),54 signal transduction during neuronal development (GDAP1, which encodes ganglioside induced differentiation associated protein 1), neurotransmission (GRIN2B [coding for NMDA receptor subtype 2B], OPRM1 [coding for μ-opioid receptor], POMC (coding for proopiomelanocortin), SLC6A3 (coding for dopamine transporter), and SLC6A4 [coding for serotonin transporter]), endoplasmic reticulum (ER) stress response (HERP, which encodes homocysteine-induced endoplasmic reticulum protein),55 monoamine oxidization (MAOA, which encodes monoamine oxidase A), sleep and arousal regulation (Orexin A, which encodes hypothalamic neuropeptide orexin A),56 or presynaptic signaling and membrane trafficking (SNCA, which encodes synuclein, alpha).57 Hillemacher et al.58 compared AVP and ANP promoter DNA methylation differences between 111 AUD cases and 57 healthy controls. They reported a significant increase in AVP promoter DNA
