Genome-wide association studies are huge undertakings that compare the genomes of large populations. They can turn up thousands to tens of thousands of genetic variants associated with disease. But which GWAS variants really matter?
That question becomes exponentially harder when the variants lie in the vast stretches of DNA that don’t encode proteins, but instead have regulatory functions.
“It’s hard to know which hits are causal hits, and which are just going along for the ride,” says Vijay Sankaran, MD, PhD, a pediatric hematologist/oncologist at Dana-Farber/Boston Children’s Cancer and Blood Disorders Center and an associate member of the Broad Institute.
Reporting in Cell, Sankaran’s team and two other groups at the Broad Institute describe a new tool that can looks at hundreds of thousands of genetic elements at once to pinpoint variants that truly affect gene expression or function. Called the massively parallel reporter assay (MPRA), it could help reveal subtle genetic influences on diseases and traits.
In Sankaran’s case, the MPRA is helping him understand how common variants contribute to blood disorders in children. “Most of the common variation is just tuning genetic function,” he says. “Just slightly, not turning it on or off, but actually just tuning it like a dimmer switch.”
The above video explains how the assay works – via DNA “barcodes.” Read more on the Broad Institute’s blog, Broad Minded.