GRN and frontotemporal dementia: Similarly, a loss of myelin sphingolipids was found in FTD patients carrying a progranulin mutation, and a mouse model of FTD lacking progranulin showed changes in the activity of enzymes involved in sphingolipid metabolism, which strongly suggests the implication of such genes in maintaining oligodendroglial function (Huang et al., 2020; Lok and Kwok, 2021).