APTX and osteosarcoma: CRISPR-Cas9-mediated knockout (KO) of APTX in human osteosarcoma cell line U2OS disrupted mitochondrial morphology, mitochondrial networks, decreased mitochondrial membrane potential (MMP) and increased reactive oxygen species (ROS) production, leading to impaired mitophagy (Akbari et al., 2015), also seen in AOA1 patient cell lines (Zheng et al., 2019).