B4GALNT1 and hereditary spastic paraplegia: As well as the cholesterol/oxysterol and PE/PC pathways defined here, accumulating evidence identifies disturbances in sphingolipid (in particular glycosphingolipid) metabolism in a growing number of neurological diseases including HSP/MND (e.g. FA2H, B4GALNT1) (Harlalka et al., 2013) and GBA2 (Sultana et al., 2015), which may potentially involve disruption of myelin integrity.