Genetics that control size of brain regions linked with Parkinson’s risk
Differences may impact development of disorders that affect the brain
Genetic variations that influence the size of specific brain regions are associated with an increased risk of developing Parkinson’s disease, a study reports.
“Our findings suggest that genetic influences that underpin individual differences in brain structure may be fundamental to understanding the underlying causes of brain-related disorders,” Miguel Rentería, PhD, co-author of the study at the Queensland Institute of Medical Research in Australia, said in a news release.
The study, “Genomic analysis of intracranial and subcortical brain volumes yields polygenic scores accounting for variation across ancestries,” was published in Nature Genetics.
The brain is an extremely complex organ and many individual regions and compartments help control specific parts of the body and regulate consciousness. Although everyone has the same brain regions, the size of each individual region can vary from person to person.
These differences might theoretically impact the development of disorders like Parkinson’s that affect the brain. Little is known about what causes individual brain regions to be bigger or smaller in different people.
Role of genetics in brain region size
Here, researchers investigated whether genetics might play a role in determining brain region size using a type of analysis called a genome-wide association study, or GWAS, which involves looking for specific genetic mutations that are more or less common in people with a certain trait (i.e., bigger or smaller brain regions), which suggests the particular variant helps control that trait.
“A lot of brain diseases are known to be partially genetic, but from a scientific point of view, we want to find the specific changes in the genetic code that cause these,” said Paul Thompson, PhD, study co-author at the University of Southern California.
The GWAS included data on nearly 75,000 people, with the researchers looking for associations with regions in nine different parts of the brain, including several impacted in Parkinson’s like the putamen and caudate nucleus. The results identified 254 genetic variations with statistically significant links to the size of different brain regions.
The main GWAS included only people of European ancestry, but additional analyses with a separate cohort of more than 5,000 people of diverse ancestries yielded similar results, suggesting these genetic associations are consistent across ethnic groups.
“By conducting this research all over the world, we’re beginning to home in on what has been called ‘the genetic essence of humanity,’” Thompson said.
After identifying the genetic predictors of brain region size, the researchers conducted additional analyses to see if there was overlap between genes that control the size of brain regions and genes that are known to be associated with neurological conditions like Parkinson’s. Statistically significant associations between genes linked with larger size in several brain regions and higher Parkinson’s risk were seen.
The findings, “suggest that genetic variants influencing larger volumes during the development of specific structures [in the brain] are also associated with a higher risk for Parkinson’s disease,” wrote the researchers, who noted statistical connections between brain size genes and other conditions such as attention-deficit hyperactive disorder (ADHD). The correlations don’t prove a cause and effect relationship, but the data suggest the size of individual brain regions may impact the development of neurological conditions.
“There is strong evidence that ADHD and Parkinson’s have a biological basis, and this research is a necessary step to understanding and eventually treating these conditions more effectively,” Rentería said.
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