Treutlein et al., 2009 conducted a GWAS of alcohol dependence which consisted of a German sample of males with an early age of onset of DSM-IV alcohol dependence (Treutlein et al., 2009). Age of onset was younger than 28 years and each case (n = 487) had alcohol dependence that required hospitalization for the treatment of severe withdrawal symptoms. Control subjects (n = 1358) were derived from three population-based epidemiologic studies conducted in the same geographical location and were ascertained as general population based controls for various biomedical studies. However, it is important to note that Treutlein et al., 2009 do not provide data on whether the population-based control subjects used in their GWAS of alcohol dependence were screened for psychiatric disorders including substance and alcohol use disorders. A total of 524,396 SNPs were tested in the case-control sample for association with alcohol dependence. There were no genomewide significant SNP associations observed (p < 10–8). However, 120 SNPs with a P < 10–4 were selected for genotyping in a follow-up sample of German males with DSM-IV alcohol dependence (age of
