SPTBN2 and hypomyelinating leukodystrophy 6: Pathogenic mutations in SPTBN2, KIF1A, and TUBB4A were already known to cause SCA5 (OMIM # 600224), autosomal recessive SPG30 (OMIM # 610357), and both autosomal dominant type 4 dystonia (OMIM # 128101) and type 6 hypomyelination leukodystrophy (OMIM # 612438), respectively (Ikeda et al., 2006; Erlich et al., 2011; Hersheson et al., 2013; Simons et al., 2013).