Genetic testing for cardiomyopathy less accurate for minorities

Genetic testing for cardiomyopathy in the United States works significantly better for whites than minorities, according to a report published online Feb. 28 in JAMA Cardiology.

Latrice G. Landry, PhD, and Heidi L. Rehm, PhD—both with Partners Healthcare Personalized Medicine in Cambridge, Massachusetts—analyzed genetic test results from 5,729 individuals with a suspected diagnosis or family history of cardiomyopathy referred for testing at their institution from 2003 through 2017.

They found genetic testing detected the likely cause of cardiomyopathy in 29 percent of whites, 25 percent of Asians and 18.4 percent of other minorities—a combination of blacks, Hispanics, Native Americans, Alaska Natives, Hawaiians and other South Pacific Islanders. Individuals of mixed race/ethnicity were excluded from the analysis.

In addition, Landry and Rehm reported inconclusive test results were higher for minorities. The combined minority group had the highest rate of inconclusive tests (39.8 percent), followed by Asian individuals (39.2 percent) and whites (24.6 percent).

“This suggests greater clinical usefulness of genetic testing for cardiomyopathy in white persons in comparison with people of other racial/ethnic groups,” the authors wrote. “This clear disparity warrants further study to understand the gaps in usefulness, which may derive from a lack of clinical testing and research in underrepresented minority populations, in the hopes of improving genetic testing outcomes for cardiomyopathy in nonwhite groups.”

The researchers acknowledged their study was limited by a difference in sample size across the racial groups—79.2 percent of the cohort were white, 6.1 percent were of Asian ethnicity and 14.7 percent were other minorities. The proportion of people in each group was reflective of referral rates, the authors noted, not random sampling.

“The obvious remedy for this dearth of data is to sequence large numbers of well-phenotyped cases and controls from economically, ethnically, and racially diverse populations,” a trio of researchers led by Glenn S. Gerhard, MD, wrote in an accompanying viewpoint. “This appears to be progressing much more rapidly now on the research front, where resources are being specifically directed at specific populations or cohorts of patients.”

In a related editorial, three authors from the Center for Genetic Medicine at Northwestern University pointed out several research efforts are underway to better represent the black and Hispanic populations. Specifically, they highlighted National Heart, Lung, and Blood Institute’s Trans-Omics for Precision Medicine, the All of Us Research Program of the National Institutes of Health and the Million Veteran Project of the U.S. Veterans Administration.

“Without sufficient data from a racially/ethnically matched population, pathogenic or likely pathogenic variants cannot be adequately evaluated,” wrote the editorialists, including Elizabeth M. McNally, MD, PhD, an associate editor of JAMA Cardiology. “When this occurs, patients and families are not afforded the value of having a genetic diagnosis, which may include delineation of risk for sudden cardiac death.”

Gerhard et al. also noted insurance coverage plays a role in which underserved populations can afford genetic testing, although at least one genetic testing company offers a wide array of services for individuals below certain income thresholds through Medicare and Medicaid. Eliminating financial barriers to genetic testing could allow for more equal benefit across all racial groups, they wrote.