In the other three studies, TS identified mutations in SPTBN2, KIF1A, and TUBB4A as the causes of SCAR14 (OMIM # 615386), the autosomal dominant form of SPG30 (OMIM # 610357), and TUBB4A-associated SPG, respectively (Lise et al., 2012; Ylikallio et al., 2015; Sagnelli et al., 2016). Here, KIF1A is linked to hereditary spastic paraplegia.