In Munich and Bonn, patients were assessed using the Semi Structured Assessment for Genetics of Alcoholism (SSAGA),29 in Mainz the Composite International Diagnostic Interview (CIDI)30 was used, in Regensburg, Essen/Düsseldorf/Homburg and Mannheim the Structured Clinical Interview for DSM31 was used. The latter tool was also applied in Munich. All patients and controls were of self reported German ancestry. The study was approved by all relevant local Ethics Committees and all subjects provided written informed consent. In order to increase the power of the study, we increased the homogeneity of the patient sample by including male patients only. Furthermore, only subjects with an early age at onset of alcohol dependence were included, a feature which has a higher heritability in males.32,33Patients included in the GWAS (Mannheim N=98; Bonn/Essen/Düsseldorf/Homburg N=30; Mainz N=30; Munich N=53; and Regensburg N=276) had an age at onset <28 (median=20, mean±std=21±4.1) years, defined as the age at which DSM-IV criteria for alcohol dependence were fulfilled for the first time.
