TAFAZZIN and Barth syndrome: The counterbalance of a plasmenylethanolamine loss by a gain of diacyl PE observed in other TAZ-KD mouse organs and in the lymphoblast of BTHS patients, where ethanolamine is the dominant class of plasmalogen, may be similarly explained by feedback regulation by the two products to the EPT activity, that is, plasmanylethanolamine and diacyl PE (Figs 1C and S2); a loss of plasmenylethanolamine causes feedback regulation on plasmanylethanolamine desaturase to possibly result in a loss of the substrate plasmanylethanolamine.