(A) After treatment of 250 nM ML240 for 6 hr, Mfn 1 level of VCPR155H/+ IBMPFD patient fibroblasts is elevated from 0.77 ± 0.02 to 1.05 ± 0.11 (p=0.037, independent t test, N = 3), as compared with healthy controls, for which values are set as 1. (B) After treatment with 250 nM ML240 for 6 hr, the mitochondria fusion assay shows that the decreased mitochondrial fusion observed in IBMPFD patient’s fibroblasts is significantly reversed (independent t test, *p<0.05). (C) 50 nM and 100 nM ML240 treatment for 4 days significantly increases basal (p=0.0001, DMSO v.s. 50 nM ML240; p=0.0027, DMSO v.s. 100 nM ML240, Welch's unpaired t test, N = 8) and maximal oxygen consumption rate (p=0.0415, DMSO v.s. 50 nM ML240; p=0.0028, DMSO v.s. 100 nM ML240, Welch’s unpaired t test, N = 8) in the IBMPFD patient fibroblasts harboring VCPR155H/+ mutation. (D) 1 nM and 10 nM NMS-873 treatment for 6 days significantly increases maximal oxygen consumption rate (p=0.0021, DMSO v.s. 1 nM NMS-873; p=0.0395, DMSO v.s. 10 nM NMS-873, N = 8), but not basal oxygen consumption rate (p=0.0994, DMSO v.s. 1 nM NMS-873; p=0.1804, DMSO v.s. 10 nM NMS-873, N = 8). Welch’s unpaired t test is used. *p<0.05, **p<0.01, n.s, no statistical significance.