FTLD-TDP-43 With Motor Neuron Disease Pathology in an Autopsied Patient With Spastic Paraplegia-30B Harbouring a Homozygous KIF1A Variant.

KIF1A-associated neurological disorder (KAND) is a rare hereditary condition caused by KIF1A variants, affecting axonal transport and presenting with a wide clinical spectrum, including hereditary spastic paraplegia. This case of childhood-onset KAND reveals FTLD-TDP43 with motor neuron disease pathology emerging late in the disease course, suggesting that HSP and FTLD-MND share a pathological continuum through a TDP-43-related pathway and expanding the clinicopathological spectrum of KAND.