Given (i) that rs1990622-A increases the risk for FTD, particularly in people with heterozygous GRN mutations [73], and (ii) these GRN mutations are associated with substantially lower myelin sphingolipid content in people with FTD [39], it would also be of interest to determine if these rare GRN mutations are also associated with lower myelin sphingolipid content in cognitively normal human donors, and how this is affected by rs1990622-A. Here, GRN is linked to frontotemporal dementia.