Based on limited published evidence, HTD2 encodes a mitochondrial 3-hydroxyacyl-thioester dehydratase involved in fatty acid biosynthesis. The enzyme catalyzes (3R)-specific hydratase activity on hydroxyacyl-CoA and hydroxyacyl-ACP substrates within the mitochondrial matrix 1. HTD2 is essential for mitochondrial respiratory competence and proper morphology 2. Notably, human HTD2 is encoded by a conserved bicistronic transcript with RPP14, linking mitochondrial fatty acid synthesis to RNA processing across 400 million years of vertebrate evolution 1.