In this multicenter cohort study of 117 adult patients with dilated cardiomyopathy, 13 of 28 patients with titin-truncating variants (46%) received 1 or more appropriate implanted cardioverter defibrillator therapies compared with 13 of 89 patients without titin-truncating variants (16%), a significant difference. The gene discussed is TTN; the disease is dilated cardiomyopathy.