KIF5A and hereditary spastic paraplegia: Either way, the fact that kinesin-1A appears to be a neurofilament motor and that N256S-kinesin-1A disrupts the bidirectional transport of neurofilaments in cultured neurons suggest that patients with the SPG10 form of hereditary spastic paraplegia may well have neurofilament transport abnormalities which may contribute to the disease progression, and this warrants further investigation.