PPCS and Pelizeaus-Merzbacher spectrum disorder: The questionnaire did not include vitamin B5 (pantothenate), which has recently been suggested as a treatment for some disorders of CoA biosynthesis (e.g., phosphopantothenoylcysteine synthetase (PPCS) deficiency34) and together with other B vitamins for TANGO2 deficiency, a PMD mimic with potentially lethal cardiac manifestations.35, 36