Genetics: Large GWAS identifies variants associated with drinking and smoking

Nearly 4,000 genetic associations for smoking and drinking behaviours have been identified in a multi-ancestry genome-wide association study (GWAS) involving almost 3.4 million individuals. The findings, published in Nature this week, shed more light on potential genetic influences on these complicated behaviours.

Smoking and drinking are major risk factors for various diseases and disorders. Although they can be affected by environmental factors such as cultural context and public health policies, there is strong evidence that genetics also contributes to tobacco and alcohol use. Previous GWASs, in which genetic data from many people are compared to identify potentially relevant genes, focused largely on individuals of European ancestry, whereas little is known about the genetic contribution to these behaviours in other populations.

Scott Vrieze, Dajiang Liu and colleagues assembled and analysed GWAS data from 60 cohorts containing almost 3.4 million individuals representing 4 ancestry groups (African, American, East Asian and European ancestries). More than 20% of the study cohort are from non-European ancestries. They identified nearly 4,000 genetic variants that are associated with smoking or drinking behaviours, including the age at which individuals started smoking and the number of alcoholic drinks consumed per week. The researchers found that the majority of these variants showed consistent effects across different ancestries. However, polygenic scores (a measure of genetic association based on the collective influence of multiple genetic variants), when trained on data from individuals with European ancestry, had reduced predictive performance in populations without European ancestry compared to those with European ancestry. This finding suggests that the transferability of such scores across ancestries remains challenging.

The findings improve our understanding of genetic factors associated with smoking and drinking behaviours and highlight the importance of increased sample size and diverse ancestry in such studies.