Furthermore, we and other groups have recently found several E3 ubiquitin ligases, including Cbl, Nedd4, and RNF43, that are involved in oligodendroglial differentiation and (re)myelination (23, 37, 38), though genetic epidemiology studies have so far not found any pathological mutation in these genes in patients with HLD. This evidence concerns the gene PRKN and leukodystrophy.