💡What To Know:
- 3 specific genetic variants offer protective benefits against excessive alcohol drinking.
- People with alcohol-protective genetic variants had better overall health
- However, they also had increased risks for certain conditions like tobacco use, emotional eating, hyperthyroidism, and cancer.
SAN DIEGO — The relationship between a person’s genes and drinking habits is both nuanced and complex. As modern science continues to wrestle with this intricate topic, researchers at the University of California San Diego School of Medicine have performed a deep dive into the alcohol consumption trends of over three million people gathered by direct-to-consumer genetics company 23andMe. The team discovered several connections between genetic factors that influence drinking and their relationship with other disorders.
Sandra Sanchez-Roige, Ph.D., corresponding author and associate professor at UC San Diego School of Medicine Department of Psychiatry, explains that this study used genetic data to broadly classify individuals as either European, Latin American, or African American.
The classifications “are needed to avoid a statistical genetics pitfall called population stratification,” notes co-author Abraham A. Palmer, Ph.D., professor and vice chair for basic research in the psychiatry department, in a university release.
Researchers analyzed a genetic dataset of three million 23andMe research participants, all while placing a special emphasis on three specific little snippets of DNA known as single-nucleotide polymorphisms (SNPs). Prof. Sanchez-Roige explains that variants, or alleles, of these particular SNPs offer protective benefits against a variety of alcohol behaviors, including excessive alcohol drinking and alcohol use disorder.
One of the alcohol-protective variants is very rare. The most prevalent among the three alleles found in the study showed up in just 232 individuals among the 2,619,939 European cohort, 29 of the 446,646 Latin American cohort, and seven of the 146,776 African American cohort. The others are much more common. These variants influence how the body metabolizes ethanol, the intoxicating chemical in alcohol.
“The people who have the minor allele variant of the SNP convert ethanol to acetaldehyde very rapidly. And that causes a lot of negative effects,” Prof. Sanchez-Roige adds.
Sanchez-Roige notes the resulting nausea eclipses any pleasurable effects of alcohol, similar to a bad hangover that sets in almost immediately.
“These variants are primarily associated with how much someone may consume alcohol,” the researcher continues. “And they also tend to prevent alcohol use disorder, because these variants are primarily associated with the quantity of alcohol someone may drink.”
Prof. Sanchez-Roige notes the SNP variants’ influence on alcohol consumption is well researched, but her group adopted a “hypothesis-free” approach to the 23andMe dataset, which also featured survey data pertaining to thousands of traits and behaviors. The research team wanted to figure out if the three SNP variants might induce any other effects beyond alcohol consumption.
Researchers say their group has worked to develop a 10-year partnership with 23andMe, focusing on numerous areas and traits, particularly those with any relevance to addiction. This study was possible thanks to an academic collaboration through the 23andMe Research Program.
Study authors data-mined the analyses of DNA from saliva samples submitted by consenting 23andMe research participants, in addition to survey responses regarding health and behavior available from the 23andMe database. This led to the discovery of a cluster of associations, not all necessarily connected with alcohol. People with the alcohol-protecting alleles generally had stronger health, including less chronic fatigue and requiring less daily assistance with daily tasks.
However, the study also finds people with the alcohol-protective alleles had worse health outcomes across certain areas, including more lifetime tobacco use, more emotional eating, more Graves’ disease, and hyperthyroidism. Those with the alcohol-protective alleles also reported totally unexpected differences like more malaria, more myopia, and several cancers (particularly more skin cancer and lung cancer) and more migraine with aura.
Prof. Sanchez-Roige acknowledges that there is something of a chicken-and-egg aspect to these findings. For instance, cardiovascular disease is just one of a number of maladies showing an association with alcohol consumption.
“So is alcohol consumption leading to these conditions?” Sanchez-Roige asks.
“Or do these genetic differences influence traits like malaria and skin cancer in a manner that is independent of alcohol consumption?” Prof. Palmer continues.
Prof. Sanchez-Roige stresses that such broad, hypothesis-free studies are only possible if researchers are granted access to very large sets of data. Many datasets, including the one used for this study, rely heavily on individuals with European ancestry.
“It is important to include individuals from different ancestral backgrounds in genetic studies because it provides a more complete understanding of the genetic basis of alcohol behaviors and other conditions, all of which contributes to a more inclusive and accurate understanding of human health,” Prof. Sanchez-Roige says. “The study of only one group of genetically similar individuals (for example, individuals of shared European ancestry) could worsen health disparities by aiding discoveries that will disproportionately benefit only that population.”
Moving forward, this work opens numerous doors for future research, shedding light on possible connections between alcohol-protective alleles and conditions that have no obvious connection with alcohol consumption.
“Understanding the underlying mechanisms of these effects could have implications for treatments and preventative medicine,” Prof. Sanchez-Roige concludes.
The study is published in the journal EBioMedicine.