For example, FUNDC1 deficiency caused heart failure in mice due to reduced MAMs formation and mitochondrial Ca2+ level (Wu et al., 2017); conversely, the heart function is restored in STZ-induced diabetes mellitus mice when FUNDC1 is deleted, owing to decreased MAMs formation and mitochondrial Ca2+ level (Wu et al., 2019). The gene discussed is FUNDC1; the disease is heart failure.