The current study's goal was to explore whether the inclusion of genetic information would further improve this model's ability to predict alcohol initiation. Variation in the gene encoding gamma-aminobutyric acid receptor (GABRA2) on chromosome 4 has been one of the most replicated predictors of alcohol-related phenotypes (Enoch, 2013). GABRA2 studies have been conducted on both populations outside of (Enoch, 2008; Fehr et al., 2006; Philibert et al., 2009; Soyka et al., 2008) as well as within COGA (Covault, Gelernter, Hesselbrock, Nellissery, & Kranzler, 2004; Dick, Agrawal, et al., 2006; Dick, Bierut, et al., 2006; Edenberg et al., 2004). Previous COGA studies, using a different study population than that of the current investigation, found that the adenine (A) nucleotide for SNP rs279871 was associated with an increased risk for adult AD (Edenberg et al., 2004), with the greatest risk occurring in individuals who were homozygous for this allele (Dick, Agrawal, et al., 2006). These data suggested that the A allele (the T allele on the complementary strand examined in the current study) could potentially be a risk allele for early initiation
