Cardiogenetics

For Genetic Tests, Size Matters 

next gen sequencing

A study in JAMA Cardiology found that broader genetic tests are better at identifying patients with cardiomyopathies and arrhythmias than disease-specific tests, despite perceived drawbacks. 

Currently, physicians typically use tests that are designed to find a specific type of cardiomyopathy or a specific type of arrhythmia. This is because examining a larger slice of a person’s genome will inherently capture a greater number of genetic mutations, and sometimes clinicians do not know what the impact of a genetic change will be on the patient’s risk. 

This uncertainty can create confusion for both the clinician and the patient. The authors of an editorial on the study explain that these “gray zone” variants are often seen as the price you pay for broader tests. 

But this retrospective study challenges that outlook. Physicians ordered combined cardiomyopathy and arrhythmia genetic testing for 4,789 patients and found that the combined testing identified clinically relevant variants for 1 in 5 patients:

  • 954 of 4,789 (20%) were flagged as a “positive” result.
  • 66% of these positives (630 patients) provided meaningful information that could inform clinical decision-making.
  • If testing had been restricted to panels associated with the clinician-provided diagnostic indications, 75 of 689 positive results (11%) would have been missed.

The Takeaway

In contrast to typical practice, it appears that more comprehensive genetic panels produce meaningful insights that could guide physician decision-making. When it comes to testing for cardiomyopathies and arrhythmias, the added burden of uncertainty may be worth it.

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-- The Cardiac Wire Team