A genome-wide association study of almost 3.4 million people with diverse ancestries has identified 3,823 genetic variants linked to alcohol and tobacco use.
Published in Nature, the research was led by a team from the University of Minnesota, Minneapolis, and Pennsylvania State College of Medicine and collaborators from industry and other academic institutions.
The study incorporated the genetic data of almost 3.4 million people with African, American, East Asian, and European Ancestry. Participants were from 60 different cohorts across the globe, including consented research participants from 23andMe.
This is the first study of its kind to include such a diverse population. It updates work done by the same team in 2019 that primarily relied on data from people of European Ancestry.
Genetic architecture of substance use
Smoking and drinking are leading causes of mortality worldwide and are risk factors for many chronic conditions and psychiatric disorders. Though both behaviors can be influenced by environment and culture, evidence suggests genetics plays a role, too.
The researchers identified 3,823 genetic variants from more than 2,000 genomic regions linked with smoking or drinking traits. More than 2,400 were associated with the likelihood of ever smoking regularly, 243 with the number of cigarettes smoked per day, and 849 with the number of alcoholic drinks consumed per week.
When they compared these genetic variants across the different ancestries, they found striking similarities, indicating that “the genetic architecture underlying substance use is not markedly different across ancestries.”
However, they also noted that polygenic risk scores (DNA-based tools that enhance the ability to predict the risk of certain diseases) developed from people of European Ancestry couldn’t accurately predict alcohol and tobacco use in people of other ancestries.
Diversity is key
Beyond furthering the understanding of substance use and related behaviors, this work also shows how diverse population samples can increase the scope and power of genetic research.
Working with an expanded database allowed the researchers to pinpoint more genetic variants that are strongly linked to alcohol and tobacco use. And by including population samples from a wide variety of ancestry groups, these gene variants were able to be found more quickly.
“Our results highlight that inclusion of individuals of diverse genetic ancestries allows for a better understanding of the genetic architecture of substance use by increasing power to detect variants associated with these behaviors and by improving the generalizability of our findings,” said Gretchen Saunders, a psychologist at the University of Minnesota, Minneapolis, and a co-author of the paper.
“As we continue to expand [upon this research], we hope to further include individuals who better represent overall global diversity which would allow for the creation of more equitable genetic risk scores, for example.”
You can read the full paper here.