A team of Harvard Medical School researchers had noted that there were more variants determined to be pathogenic for hypertrophic cardiomyopathy than would be expected given its prevalence in the general population. Harvard's Isaac Kohane tells NPR that hypertrophic cardiomyopathy affects about one in 500 people, but "we saw that the variants that were ostensibly causing disease seemed to add up to much more than one in 500."
By examining publicly available exome and other data, Kohane and his colleagues found that a number of variants previously been thought to be causal for hypertrophic cardiomyopathy were actually benign. And many of these variants were among African Americans, meaning that African Americans who underwent genetic testing for hypertrophic cardiomyopathy were more likely to have received a false positive result.
The misidentification of these variants likely occurred when hypertrophic cardiomyopathy patients were compared to healthy controls, the patient group contained more people with African ancestry than the control group, so the study picked up differences between the groups that weren't due to hypertrophic cardiomyopathy, NPR notes. Kohane tells them the problem could've been avoided if four or five people of African descent had been included in the healthy control population.
"From the vantage point of one who sits on several federal advisory bodies in the field of genetics, the importance of more extensive genomic sequencing in diverse populations cannot be over-emphasized," Kenneth Offit from Memorial Sloan Kettering Cancer Center tells the New York Times.