title: BDNF SNPs are implicated in comorbid alcohol dependence in schizophrenia but not in alcohol-dependent patients without schizophrenia.
abstract: OBJECTIVE
  The functional BDNF single nucleotide polymorphism (SNP) rs6265 has been associated with many disorders including schizophrenia and alcohol dependence. However, studies have been inconsistent, reporting both positive and negative associations. Comorbid alcohol dependence has a high prevalence in schizophrenia so we investigated the role of rs6265 in alcohol dependence in Australian populations of schizophrenia and alcohol-dependent patients.
  
  
  METHODS
  Two BDNF SNPs rs6265 and a nearby SNP rs7103411 were genotyped in a total of 848 individuals. These included a schizophrenia group (n = 157) and a second schizophrenia replication group (n = 235), an alcohol-dependent group (n = 231) that had no schizophrenia diagnosis and a group of healthy controls (n = 225).
  
  
  RESULTS
  Allelic association between rs7103411 and comorbid alcohol dependence was identified (P = 0.044) in the primary schizophrenia sample. In the replication study, we were able to detect allelic associations between both BDNF SNPs and comorbid alcohol dependence (rs6265, P = 0.006; rs7103411, P = 0.014). Moreover, we detected association between both SNPs and risk-taking behaviour after drinking (rs6265, P = 0.005; rs7103411, P = 0.009) and we detected strong association between both SNPs and alcohol dependence in males (rs6265, P = 0.009; rs7103411, P = 0.013) while females showed association with multiple behavioural measures reflecting repetitive alcohol consumption. Haplotype analysis revealed the rs6265-rs7103411 A/C haplotype is associated with comorbid alcohol dependence (P = 0.002). When these SNPs were tested in the non-schizophrenia alcohol-dependent group we were unable to detect association.
  
  
  CONCLUSIONS
  We conclude that these BDNF SNPs play a role in development of comorbid alcohol dependence in schizophrenia while our data do not indicate that they play a role in alcohol-dependent patients who do not have schizophrenia.
authors.affiliation: Institute of Health and Biomedical Innovation, Queensland University of Technology, 60 Musk Ave., Kelvin Grove, QLD 4059, Australia.
authors.forename: Sern-Yih
authors.initials: SY
authors.lastname: Cheah
authors.affiliation: Institute of Health and Biomedical Innovation, Queensland University of Technology, 60 Musk Ave., Kelvin Grove, QLD 4059, Australia Discipline of Psychiatry, Royal Brisbane and Women's Hospital, Herston, QLD 4006, Australia.
authors.forename: Bruce R
authors.initials: BR
authors.lastname: Lawford
authors.affiliation: Institute of Health and Biomedical Innovation, Queensland University of Technology, 60 Musk Ave., Kelvin Grove, QLD 4059, Australia.
authors.forename: Ross McD
authors.initials: RM
authors.lastname: Young
authors.affiliation: Discipline of Psychiatry, Royal Brisbane and Women's Hospital, Herston, QLD 4006, Australia Centre for Youth Substance Abuse, University of Queensland, Herston, QLD 4006, Australia.
authors.forename: Jason P
authors.initials: JP
authors.lastname: Connor
authors.affiliation: Institute of Health and Biomedical Innovation, Queensland University of Technology, 60 Musk Ave., Kelvin Grove, QLD 4059, Australia.
authors.forename: C
authors.initials: C
authors.lastname: Phillip Morris
authors.affiliation: Institute of Health and Biomedical Innovation, Queensland University of Technology, 60 Musk Ave., Kelvin Grove, QLD 4059, Australia j.voisey@qut.edu.au.
authors.forename: Joanne
authors.initials: J
authors.lastname: Voisey
mesh_terms: D000328:Adult; D000428:Alcohol Drinking / Q000235:genetics / Q000523:psychology; D000437:Alcoholism / Q000453:epidemiology* / Q000235:genetics*; D000483:Alleles; D001315:Australia / Q000453:epidemiology; D019208:Brain-Derived Neurotrophic Factor / Q000235:genetics*; D016022:Case-Control Studies; D017831:Diagnosis, Dual (Psychiatry); D005260:Female; D020022:Genetic Predisposition to Disease / Q000235:genetics*; D006239:Haplotypes; D006801:Humans; D008297:Male; D008875:Middle Aged; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D012309:Risk-Taking; D012559:Schizophrenia / Q000453:epidemiology* / Q000235:genetics*; D012737:Sex Factors; D044465:White People / Q000235:genetics; D055815:Young Adult
chemical_list: D019208:Brain-Derived Neurotrophic Factor; C579455:BDNF protein, human