Consistent with the abnormal accumulation of NFs in the cell body in KIF5A knockout mice (Xia et al., 2003) and altered NF transport in KIF5A KO neurons (Uchida et al., 2009), overexpression of KIF5A mutants (as identified in the SPG10 disease, a form of human hereditary spastic paraplegia) evidenced a defect in the frequency of NF transport along the axon (Wang and Brown, 2010). This evidence concerns the gene KIF5A and hereditary spastic paraplegia.