KIF1A and Spasticity: Pathogenic variants in the KIF1A gene are responsible mainly for three phenotypes—autosomal recessive and dominant spastic paraplegia 30 (SPG30, OMIM 610357), autosomal recessive hereditary sensory and autonomic neuropathy type 2 (HSN2C, OMIM 614213), and autosomal dominant neurodegeneration and spasticity with or without cerebellar atrophy or cortical visual impairment syndrome NESCAVS (OMIM 614255).