The described mutations in APOPT1 affect coding exons 2 and 3, producing truncated protein products, either by nonsense mutations, exon 2 skipping or exon 3 deletion; except for one missense mutation (c.353T>C, p.Phe118Ser) and the deletion of one amino acid (c.370_372del, p.Glu124del). Isolated COX deficiency is the biochemical hallmark of the absence of APOPT1/COA8, which is necessary for the correct assembly of the enzyme. The APOPT1 protein levels are increased by a post-transcriptional mechanism which protects COX from oxidative stress when the production of reactive oxygen species (ROS) is increased.
APOPT1