A GABRA2 polymorphism improves a model for prediction of drinking initiation

Area of Science:

• Genetics
• Adolescent Health
• Behavioral Science

Background:

• Predicting the onset of drinking in adolescents is crucial for early intervention.
• Genetic factors, such as single nucleotide polymorphisms (SNPs), are increasingly recognized for their role in alcohol initiation.
• The GABRA2 gene, specifically the rs279871 variant, has been linked to alcoholism and risky behaviors.

Purpose of the Study:

• To investigate the predictive power of a GABRA2 SNP (rs279871) and covariates on adolescent alcohol initiation.
• To refine a previously established model for predicting early drinking onset by incorporating genetic and environmental factors.

Main Methods:

• Survival analysis using a Cox proportional hazards model was applied to a subsample of 674 adolescents (ages 14-17) from the Collaborative Study on the Genetics of Alcoholism (COGA).
• The model incorporated predictors such as conduct disorder symptoms, family history of alcohol dependence, peer drinking, and Achenbach Youth Self Report (YSR) scores, along with the GABRA2 rs279871 SNP.
• Model parsimony was determined using likelihood ratio tests and model fit statistics.

Main Results:

• The final predictive model included conduct disorder symptoms, family history of alcohol dependence, most best friends drank (MBFD), YSR externalizing score, and the recessive GABRA2 rs279871 TT genotype.
• Adolescents with the high-risk TT genotype were found to be more likely to initiate drinking compared to those without this genotype.
• YSR social problems score was not a significant predictor in the final model.

Conclusions:

• The genetic effect of the GABRA2 rs279871 TT genotype on adolescent alcohol initiation is additive with environmental factors, such as peer drinking (MBFD).
• No significant genotype-by-environment interaction was observed between the GABRA2 rs279871 genotype and environmental factors after controlling for behavioral problems.
• These findings highlight the combined influence of genetic predisposition and social environment on early alcohol use.