Reduced mitochondrial oxygen consumption, decreased respiratory chain complex protein levels, and increased ROS production were also found in fibroblasts from MCAD-deficient patients and in MCAD knockout 143B osteosarcoma cells (Lim et al., 2018), supporting a role for the disruption of bioenergetics and of redox homeostasis in the pathogenesis and progression of this disorder. The gene discussed is ACADM; the disease is osteosarcoma.