Knockdown of HK2, SENP1, or VDAC1-boosted basal and/or maximal respiration in fibroblasts generated from patients with two distinct forms of Leigh syndrome (mutations in the complex I subunit NDUFS4, and in the COQ10 biosynthetic enzyme PDSS2 (ref. 24), Fig. 4a, b, Supplementary Fig. 4a–d), although the extent of increase was less than in wild-type cells. Here, PDSS2 is linked to Leigh syndrome.