Genetic testing for dilated and arrhythmogenic cardiomyopathies - A primer for cardiologists.

Genetic testing for dilated and arrhythmogenic cardiomyopathies (DCM, ACM) is increasingly important as it can refine diagnosis, inform risk stratification, and enable cascade screening. However, its clinical application remains challenging due to variable penetrance, phenotypic overlap, and marked genetic heterogeneity. This review provides a practical framework for the use of genetic testing in DCM and ACM. We outline a stepwise approach to clinical phenotyping and patient selection, review the principles of genetic testing and result interpretation, and summarize key pre- and post-test counseling considerations. We also highlight clinically important genotypes with implications for prognosis, arrhythmic risk, decisions regarding implantable cardioverter-defibrillator (ICD) implantation, family screening, and lifestyle counseling. Finally, we discuss the two-hit model that determines disease expressivity, emerging targeted therapies, and future directions in precision care.