New phenome-wide association study offers insight into autoimmune diseases

Sometimes the best way to see something is to look at it from a different angle. Scientists have begun doing just that with data from genetic studies. Traditional genome-wide association studies, or GWAS, start with a phenotype of interest and find which genetic variants are associated with it. Phenome-wide association studies, or PheWAS, metaphorically turn this on its head by starting with a genetic variant and finding which phenotypes are associated with it.

A recently published paper in the journal PLOS One illustrates the potential of using 23andMe data in this way. By starting with a genetic variant and then sorting through hundreds of seemingly unrelated health-related phenotypes, researchers can gain insight into the genetics of some health conditions and the best ways to treat them. For example, phenotypes identified in a PheWAS could help point to potential side effects of targeting a variant with a drug. With what is now the largest database in the world of genotypic and phenotypic data from people who have consented to participate in research, 23andMe is uniquely positioned for these kinds of scientific studies.

Over the last decade, ever-larger genome-wide associations have uncovered a growing list of genetic variants known to influence disease. But understanding the causal roles these variants play is often difficult to discern, and that’s where PheWAS can help.

“This approach is relevant to drug discovery when a variant is known to have a functional effect, and the available traits include conditions which have been previously studied,” according to the authors of the study in PLOS One.

The study, done by researchers with GlaxoSmithKline and 23andMe, focused on seven genetic variants in genes in the biological pathway known as TH17, which play a role in several autoimmune and infectious diseases. The researchers took each of those genetic variants and then compared them across more than 1,200 different health-related traits for more than half a million 23andMe customers who consented to participate in research.

What the researchers found were both known and new associations,  including a regulatory variant in the RORC gene associated with allergy and asthma. This association has not been reported on before. The researchers also found associations between a variant in the TYK2 gene and several conditions such as psoriasis, Crohn’s disease, and infections. It’s this association that could help for future drug targets, according to the researchers.

The researchers noted the limits of this study, but they pointed out the potential of studies like it.

“We hope that the emergence of (Electronic Medical Records)-linked biobanks with genetic data will facilitate more routine use of the PheWAS screen providing insights into drug development strategies for targeting these genes and pathways,” the researchers concluded.