CHDS is a longitudinal study of a birth cohort of 1,265 children born in the Christchurch region of New Zealand in 1977 (Fergusson & Horwood, 2001). This cohort involved 97% of children born from April 15th to August 5th, 1977 and has been assessed on 22 occasions to age 30. Data were gathered during face-to-face interviews with subjects and parents, supplemented by data from official records. Signed consent was obtained for all aspects of data collection and the study has been subject to ethical review throughout its history. The present analysis is based on data collected during assessments of the cohort in adolescence (ages 14, 15, 16, and 18) and adulthood (ages 21, 25, 30). The number of subjects assessed at these ages ranged from 953–1,025, representing between 76% and 82% of the surviving cohort at each age. Whole blood was collected from most subjects, but for ~9% of participants saliva samples were used instead (Oragene TM, DNA Genotek Inc., Ontario, Canada). DNA extractions were performed at the University of Otago, Gene Structure and Function Lab. A total of 739 CHDS subjects, contributing 4,959 repeated alcohol consumption assessments, were analyzed in genome-wide association testing.
