The GRK2-positive area in the myocardium was the greatest in the TTS group (NC, 8.0 (6.0–18.0)%; TTS, 30.0 (26.5–34.3)%; DCM, 15.0 (13.0–21.0)%, P < 0.001, Fig. 1b). The gene discussed is GRK2; the disease is familial dilated cardiomyopathy.