BACKGROUND: Twin data suggest that alcohol dependence comorbid with illicit drug dependence represents a more heritable form of the disorder. In the Collaborative Study on the Genetics of Alcoholism sample, approximately half the alcohol-dependent individuals also meet diagnostic criteria for illicit drug dependence. In this study, we tested for heterogeneity in the association between the muscarinic acetylcholine M2 receptor gene (CHRM2) and alcohol dependence, reported previously in the full sample, among the subgroups of alcohol-dependent individuals with and without comorbid drug dependence. METHODS: Family-based association tests were conducted separately (a) in individuals with alcohol dependence with comorbid drug dependence (n = 477) and (b) in individuals with alcohol dependence without comorbid drug dependence (n = 433). These subgroups were subsequently compared on other phenotypic characteristics. RESULTS: The evidence for association between CHRM2 and alcohol dependence came entirely from the subgroup of individuals with comorbid drug dependence. There was no evidence of association with CHRM2 among the alcohol-dependent individuals without drug dependence. Subsequent phenotypic analyses suggest that the subgroup of alcohol-dependent individuals with comorbid drug dependence differ on a number of other phenotypic characteristics, including several measures of the severity of their alcohol problems, personality traits and comorbid psychiatric disorders. CONCLUSIONS: These analyses provide specific genetic evidence suggesting that alcohol dependence with comorbid drug dependence represents a particularly severe form of the disorder, with higher genetic contribution to vulnerability.
BACKGROUND: Twin data suggest that alcohol dependence comorbid with illicit drug dependence represents a more heritable form of the disorder. In the Collaborative Study on the Genetics of Alcoholism sample, approximately half the alcohol-dependent individuals also meet diagnostic criteria for illicit drug dependence. In this study, we tested for heterogeneity in the association between the muscarinic acetylcholine M2 receptor gene (CHRM2) and alcohol dependence, reported previously in the full sample, among the subgroups of alcohol-dependent individuals with and without comorbid drug dependence. METHODS: Family-based association tests were conducted separately (a) in individuals with alcohol dependence with comorbid drug dependence (n = 477) and (b) in individuals with alcohol dependence without comorbid drug dependence (n = 433). These subgroups were subsequently compared on other phenotypic characteristics. RESULTS: The evidence for association between CHRM2 and alcohol dependence came entirely from the subgroup of individuals with comorbid drug dependence. There was no evidence of association with CHRM2 among the alcohol-dependent individuals without drug dependence. Subsequent phenotypic analyses suggest that the subgroup of alcohol-dependent individuals with comorbid drug dependence differ on a number of other phenotypic characteristics, including several measures of the severity of their alcohol problems, personality traits and comorbid psychiatric disorders. CONCLUSIONS: These analyses provide specific genetic evidence suggesting that alcohol dependence with comorbid drug dependence represents a particularly severe form of the disorder, with higher genetic contribution to vulnerability.
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Authors: Danielle M Dick; Fazil Aliev; Jen C Wang; Scott Saccone; Anthony Hinrichs; Sarah Bertelsen; John Budde; Nancy Saccone; Tatiana Foroud; John Nurnberger; Xiaoling Xuei; P M Conneally; Marc Schuckit; Laura Almasy; Raymond Crowe; Samuel Kuperman; John Kramer; Jay A Tischfield; Victor Hesselbrock; Howard J Edenberg; Bernice Porjesz; John P Rice; Laura Bierut; Alison Goate Journal: Biol Psychiatry Date: 2007-12-27 Impact factor: 13.382
Authors: Chella Kamarajan; Ashwini K Pandey; David B Chorlian; Niklas Manz; Arthur T Stimus; Lance O Bauer; Victor M Hesselbrock; Marc A Schuckit; Samuel Kuperman; John Kramer; Bernice Porjesz Journal: Int J Psychophysiol Date: 2015-09-18 Impact factor: 2.997
Authors: Bao-Zhu Yang; Henry R Kranzler; Hongyu Zhao; Jeffrey R Gruen; Xingguang Luo; Joel Gelernter Journal: Alcohol Clin Exp Res Date: 2008-09-30 Impact factor: 3.455