TUBB4A and leukodystrophy: Notably, biallelic variants in genes encoding OL cytoskeletal proteins are implicated in hypomyelination, with variants in TUBB4A (encoding tubulin ß4, a microtubule specific to OLs) predicted to alter tubulin polymerization and microtubule stability, causing hypomyelination with atrophy of the basal ganglia and cerebellum, a distinct hypomyelinating leukodystrophy (Simons et al., 2013).