Plasmalogens (1-alk-1'-enyl- 2-acyl-sn-glycero-3-phosphoethanolamine or 1-alk-1'-enyl-2-acyl-sn-glycero-3-phosphocholine) are abundant (4-32% of total membrane phospholipids) membrane glycerophospholipids found throughout bacterial, invertebrate and vertebrate animal kingdoms. They differ from other membrane glycerophospholipids by having an alk-1'-enyl ether-linked chain at the glycerol sn-1 carbon. Plasmalogens are critical for normal cell function and development and their levels are altered in disease states; decreased in peroxisomal disorders, Alzheimer disease and Down syndrome, and elevated in tumours. Plasmalogens can be hydrolysed into lysoplasmalogens (1-alk-1'-enyl-2-hydroxy-sn-glycero-3-phosphoethanolamine or 1-alk-1'-enyl-2-hydroxy-sn-glycero-3-phosphocholine). Lysoplasmalogens are bioactive metabolites which have membrane-perturbing and cell lysis effects. Their levels are normally maintained at very low levels in cells, with lysoplasmalogens formed by plasmalogen hydrolysis converted back to plasmalogen in a transacylation reaction (a remodelling pathway). Alternatively, lysoplasmalogen may be degraded enzymatically by several hydrolytic enzymes that includes lysoplasmalogenase (THEM86B). THEM86B catalyses the hydrolysis of the vinyl ether bond of lysoplasmenylcholine (PMCHO) and lysoplasmenylethanolamine (PMETAM) to form a fatty aldehyde and glycerophosphocholine (GPCHO) and glycerophosphoethanolamine (GPETAM) respectively. THEM86B is localised to the ER membrane of liver and small intestinal mucosal cells where it is highly active and is probably an important enzyme there, maintaining the balance between plasmalogen and lysoplasmalogen, thereby preserving membrane stability and function (Wu et al. 2011, Honsho et al. 2015).