A functional single nucleotide polymorphism (SNP) in NPY, Leu7Pro (rs16139) (Karvonen et al., 1998), has been extensively studied for its association with alcohol dependence, consumption, and withdrawal symptoms; however, results have been inconsistent. Independent studies have found that the Pro7 allele is more frequent in alcohol dependent individuals than in controls (Kauhanen et al., 2000; Lappalainen et al., 2002), more common in individuals with late onset of alcohol dependence than in those with early onset (Mottagui-Tabar et al., 2005), and more common in alcoholics experiencing severe withdrawal symptoms and higher daily alcohol consumption (Koehnke et al., 2002). In Finnish men, the same allele appeared weakly associated with higher weekly consumption of alcohol (Kauhanen et al., 2000). In contrast, the Pro7 allele when found in heterozygous form was less common among alcoholics than social drinkers (Ilveskoski et al., 2001). Other studies found no significant differences in allele frequency between alcohol dependent individuals and controls of Finnish, Swedish or German origin (Hu et al., 2005; Mottagui-Tabar et al., 2005; Zhu et al., 2003; Zill et al, 2008). Studies of human alcoholics drinking
