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Minorities in the U.S. were more likely than white patients to get inconclusive results from cardiomyopathy genetic testing, researchers found.

Compared with the 29.0% rate of positive detection among white patients, the rate was 25.0% for Asians (P=0.12) and 18.4% for other minority groups combined (P<0.001), reported Heidi Rehm, PhD, and Latrice Landry, PhD, both of Partners Healthcare Personalized Medicine in Cambridge, Massachusetts.

Inconclusive results, on the other hand, were observed for 24.6% of white patients compared with 39.2% of Asians (P<0.001) and 39.8% of other minorities (P<0.001), according to the study published online in .

"This suggests greater clinical usefulness of genetic testing for cardiomyopathy in white persons in comparison with people of other racial [or] ethnic groups. 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," Rehm and Landry wrote.

They gathered test results of 5,729 people (79.2% white, 6.1% Asian, and 14.7% of another minority group), all of whom had a suspected diagnosis or family history of cardiomyopathy. This cohort had been referred for testing at the authors' institution from 2003 to 2017.

Those of mixed or unspecified ethnicity were not included in the analysis.

Rehm and Landry cautioned that the predominance of white individuals included was a limitation to their study and may reflect differences in referrals for genetic testing. Moreover, race and ethnicity were self-reported.

Insufficiency of genetic data for non-white groups is a target for ongoing research improvement.

"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. 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," according to an accompanying viewpoint article by Glenn Gerhard, MD, of Temple University School of Medicine in Philadelphia, and colleagues.

For example, current efforts to represent the U.S. population include the National Heart, Lung, and Blood Institute's Trans-Omics for Precision Medicine, the All of Us Research Program of the NIH, and the Million Veteran Project of the U.S. Veterans Administration, Elizabeth McNally, MD, PhD, of Chicago's Northwestern University Feinberg School of Medicine, and colleagues noted in a separate accompanying editorial.

"The data that will be ultimately available from these projects will be deposited into publicly accessible databases," McNally's group wrote.

"Important caveats to these data sets are a lack of individual-level data and the unavailability of linked clinical findings. These limitations protect the privacy of biobank participants but also restrict the usefulness of the information," they continued. "To offset these limitations, many genetic testing companies now routinely deposit genetic data into ClinVar and Clinical Genome Resource, which provide expert curation on specific genetic variants, including summary data providing the rationale for the variant's designation. ClinVar and Clinical Genome Resource are efforts sponsored by the NIH that allow genetics professionals to readily evaluate and reevaluate genetic variants to ensure up-to-date classification."

Getting busy practices to start new clinical pathways to encourage more genetic testing can be a challenge, Gerhard and colleagues suggested, adding that it may be hard to convince clinicians that genetic testing is useful in the first place.

"Significant effort and appropriate experience may be required to initiate administrative processes for ordering testing, obtain preauthorization of coverage, and determine whether a patient may be at risk for out-of-pocket uncovered expenses. For many patients, even a $20 copay is a significant amount; thus, billing for a relatively expensive genetic test may represent an extreme financial burden," they wrote.