NRG3 and nicotine dependence: Genomic variants rs1937970-A (intr) and rs677221-G (intr) in the NRG3 gene are associated with an increased incidence of schizophrenia in a Han Chinese population (Wang et al., 2008), and a number of NRG3 polymorphisms, such as rs10883934-C (intr), rs1896506-A (intr) and others, correlate with the predisposition to nicotine addiction in an American population (Turner et al., 2014).