By: Juliette Blais-Savoie
Genetics has become a highly influential branch of medical science. Since the completion of the human genome project in 2003, researchers have been able to investigate the genes underlying many different diseases. Sequencing technologies have advanced even more in recent years, making sequencing a more accessible diagnostic tool for patients.
One strategy that uses genetics to investigate disease risk is the Genome Wide Association Study (GWAS). A GWAS uses sequences from a large population to investigate associations between diseases and specific genes. The goal of these studies is to find genes that are strongly associated with certain diseases, such as the BRCA1 and BRCA2 genes are associated with heightened risk of breast cancer. Once these genetic links are discovered, they can be used as a diagnostic tool to assess disease risk. For example, women who have relatives with breast cancer are often screened for BRCA1 and BRCA2.
It is important to note that just because an individual has a gene associated with a disease, it doesn’t mean that individual will inevitably become ill with that disease. These patients simply have an increased likelihood of developing that disease. This knowledge can be extremely useful for taking preventative measures in at-risk patients. Women with BRCA1 or BRCA2 are often instructed to have more frequent mammograms to detect any possible cancer developments early on, and patients who have increased risks of heart attacks may begin taking baby aspirin as a blood thinner.
While it is clear how this genetic approach can help save lives, it is unfortunately not as effective in all populations. Over 95% of the sequences in GWAS come from white patients of European heritage. This becomes problematic since genes of interest are identified by correlations within the GWAS groups, which largely exclude all people of color. While many risk-associated genes are present in all races, different mutations arose during historical periods of isolation between people of different geographic regions, largely during the prehistoric period. Because of this, mutations that are present in black or asian patients will not be investigated by GWAS, making genetic diagnostics much less accurate in POC, especially black patients, who have the fewest shared genes with white Europeans. Fortunately, this is an entirely remediable issue. Genome Wide Association Studies simply need to be made more diverse, so that patients of all genetic backgrounds can benefit from these amazing and lifesaving approaches.
National Human Genome Research Institute. Human Genome Project Timeline of Events. (2021). https://www.genome.gov/human-genome-project/Timeline-of-Events.
Nixon, C., Cottrell., P. Breast Cancer Risk Factors: Genetics. (2021). https://www.breastcancer.org/risk/factors/genetics.
Martin, A.R., Kanai, M., Kamatani, Y. et al. Clinical use of current polygenic risk scores may exacerbate health disparities. Nat Genet 51, 584–591 (2019). https://doi.org/10.1038/s41588-019-0379-x.