ClinGen — The Clinical Genome Resource

TLDR

Hypertrophic cardiomyopathy is a dominantly inherited disorder that predisposes to sudden cardiac death, and genetic testing is used to identify pathogenic variants, though variant interpretations can evolve with new population data. Using a newly available multi‑gene panel, a pathogenic variant was discovered in an affected family member, retesting identified a previously negative member as positive, and immediate clinical workup resulted in an intracardiac defibrillator implantation to mitigate sudden cardiac death risk.

Abstract

On autopsy, a patient is found to have hypertrophic cardiomyopathy. The patient’s family pursues genetic testing that shows a “likely pathogenic” variant for the condition on the basis of a study in an original research publication. Given the dominant inheritance of the condition and the risk of sudden cardiac death, other family members are tested for the genetic variant to determine their risk. Several family members test negative and are told that they are not at risk for hypertrophic cardiomyopathy and sudden cardiac death, and those who test positive are told that they need to be regularly monitored for cardiomyopathy on echocardiography. Five years later, during a routine clinic visit of one of the genotype-positive family members, the cardiologist queries a database for current knowledge on the genetic variant and discovers that the variant is now interpreted as “likely benign” by another laboratory that uses more recently derived population-frequency data. A newly available testing panel for additional genes that are implicated in hypertrophic cardiomyopathy is initiated on an affected family member, and a different variant is found that is determined to be pathogenic. Family members are retested, and one member who previously tested negative is now found to be positive for this new variant. An immediate clinical workup detects evidence of cardiomyopathy, and an intracardiac defibrillator is implanted to reduce the risk of sudden cardiac death.