This article was originally published on The Conversation, an independent and nonprofit source of news, analysis and commentary from academic experts. Disclosure information is available on the original site.
Author: Michael Mackley, Dalhousie University
Statistics Canada recently released its 2016 census data, which depicts a Canada that is more diverse than ever before. Today, nearly a quarter of Canadians belong to a “visible minority” and 1.7 million Canadians are Indigenous.
Having only recently returned to this country after finishing my PhD at the University of Oxford, where I studied genome sequencing and its impact on clinical practice, I have been constantly reminded of our diversity. And yet I know that this diversity is still entirely lacking from our genomic data.
Today, genomics is quickly becoming integrated into our health-care system. It is providing new targeted treatments for cancer, creating personalized drug regimens, and uncovering diagnoses for rare diseases that were previously genetic mysteries. However, the lack of diversity in existing genomic data limits the ability of ethnic minorities — including Indigenous Canadians — to benefit from these advances in health care. And this perpetuates the very inequalities that caused the problem in the first place.
White Canadians, incomplete databases
Our genomes are recipe books for who we are. Individual variation in our genes — like changes in individual recipes — can provide extremely useful health information. This includes information on our risk of developing serious diseases, ranging from cancers to fatal heart conditions.
Today, when a health-care provider suspects that someone may have one of these genetic illnesses, they are able to read his or her genome sequence from cover to cover. Due to decreasing costs, use of this technology has skyrocketed. Genome-based testing is helping provide diagnoses that were previously unimaginable — from new genetic causes of early-onset epilepsy and birth defects affecting the heart, to new drivers of cancer.
An important step in the analysis process is determining how often a genetic “variant” occurs in healthy people. If a variant is too common in the wider population, it is unlikely to be harmful. Although we don’t have genome data for everyone, we do have extremely large databases of genome data from healthy individuals. We can use these as stand-ins for the wider population, to determine “normal” variation and which variants may cause problems.
Unfortunately, while growing in size, these databases are imperfect. There is normal genetic variation between human groups of different geographical origin. DNA-based ancestry tests, like 23andMe, use these differences to help tell you where you are from.
Genomic databases, however, mostly contain data from individuals of European descent. As a result, the data doesn’t actually reflect the wider population, but the wider white population. This is a product of historical biases and inequalities, and has real consequences for patients from groups who aren’t well represented.
Misdiagnoses among African Americans
Hypertrophic cardiomyopathy is an inherited heart condition that can cause sudden cardiac death. Cases often make headlines when professional athletes die suddenly, like NBA-bound rising star Hank Gathers’ tragic death in 1990.
A study published last year, however, showed that some African Americans were being misdiagnosed with the disease. This was not a biological problem, but a social one. Individuals of African descent were under-represented in the databases used for comparison. Variants that health-care providers thought caused the disease, and were regularly used to provide patients with positive diagnoses, were actually found to be common among healthy African Americans.
Instead of causing disease, they were simply ethnic differences with no harmful effect whatsoever. For individuals of African descent, these variants were “normal.” Patients were sent home with diagnoses of hypertrophic cardiomyopathy who didn’t […]
(Visited 15 times, 3 visits today)