Up to now, 7 TNNI3K (troponin-I interacting kinase) variants have been reported,1–7 from which 3 with moderate-to-strong genetic evidence, for example, multigenerational cosegregation.1,2,4 Patients harboring variants in TNNI3K present with several cardiac phenotypes including dilated cardiomyopathy (DCM), cardiac conduction disease (CCD), and supraventricular tachycardias (SVT). This evidence concerns the gene TNNI3K and heart conduction disease.