NPY Leu7Pro and alcohol dependence in Finnish and Swedish populations

BACKGROUND: Neuropeptide Y (NPY) is a modulator of alcohol intake in animal models of alcoholism, and is potentially involved in alcohol dependence. A coding Leu7Pro polymorphism in the signal peptide of preproNPY has been described, and the Pro7 allele has been reported to correlate with increased alcohol consumption in non-dependent Finnish males. Recently, this polymorphism was also reported to be associated with an actual diagnosis of alcohol dependence. METHODS: We compared Pro7 allele frequencies in one Finnish (n = 135) and one Swedish (n = 472) population of alcohol dependent individuals, and ethnically matched controls (Finns: n = 213; Swedes: n = 177) in whom alcohol dependence was established, or any diagnosis of substance disorder was excluded, respectively, through the use of structured face-to-face interviews. RESULTS: Pro7 frequencies in alcoholics were 5.2 and 4.1% in Finns and Swedes, respectively, similar to the 5.0-5.5% recently reported in European Americans in a Yale study. However, corresponding frequencies in the control populations were similar, at 6.1 and 5.9% in Finns and Swedes, respectively, yielding no association, in contrast with the Yale study, where an association was reported based on a 2.0% Pro7 frequency in European American controls. A meta-analysis of available data yields Pro7 frequencies of 4.7% both in Caucasian alcoholics and Caucasian controls. CONCLUSIONS: Pro7 does not seem to be associated with a diagnosis of alcoholism in Caucasian populations.