ETFDH and multiple acyl-CoA dehydrogenase deficiency: To investigate the role of redox imbalance in MADD pathogenesis, we generated CRISPR/Cas9 knock-in <i>Drosophila melanogaster</i> models carrying patient-relevant Etf-QO missense mutations (L127R, S296C, and L399F; corresponding to human L138R, S307C, and L409F) within conserved FAD- and ubiquinone-binding domains.