DEGS1 and leukodystrophy: For example, biallelic loss-of-function mutations in DEGS1, which catalyzes the final conversion of dhCer to Cer (Figure 2A), result in increased dihydrosphingolipid levels, causing a multisystem neurological disorder of both the central and peripheral nervous systems, characterized by hypomyelination and leukodystrophy (MIM #618404) (57, 58).