Although both HCM (Gilda et al., 2016) and DCM (Rani et al., 2014) have been found in patients with TNNT2 mutations, all four zebrafish mutants seem to display only DCM-like phenotypes with atrium and ventricle enlargement (Sehnert et al., 2002; Liu et al., 2017). Here, TNNT2 is linked to familial dilated cardiomyopathy.