CAT and 3-methylglutaconic aciduria with deafness, encephalopathy, and Leigh-like syndrome: Moreover, ROS production is increased and catalase levels decreased in fibroblasts derived from at least one MEGDEL patient (Karkucinska-Wieckowska et al., 2011); therefore, similar to BTHS, defective OXPHOS function may cause an imbalance in redox homeostasis in MEGDEL patients.