PCYT2 and hereditary spastic paraplegia: The phosphate cytidylyltransferase 2, ethanolamine (SPG82/PCYT2) is involved in the complex lipid metabolism, and its mutations lead to HSP phenotypes, as PCYT2 encodes phosphoethanolamine cytidylyltransferase, playing a significant role in the CDP-ethanolamine pathway (Kennedy pathway) for phosphatidylethanolamine (PE) production.