Targeted plasma proteomics uncover proteins associated with KIF5A-linked SPG10 and ALS spectrum disorders.

KIF5A (Kinesin family member 5A) is a motor protein that functions as a key component of the axonal transport machinery. Variants in KIF5A are linked to several neurodegenerative diseases, mainly spastic paraplegia type 10 (SPG10), Charcot-Marie-Tooth disease type 2 (CMT2), and amyotrophic lateral sclerosis (ALS). These diseases share motor neuron involvement but vary significantly in clinical presentation, severity, and progression. KIF5A variants are mainly categorized into N-terminal variants associated with SPG10/CMT2 and C-terminal variants linked to ALS. This study utilized a multiplex NULISA targeted platform to analyze plasma proteome from KIF5A-linked SPG10 and ALS individuals and compare them to healthy controls. Our results revealed distinct proteomic signatures, with significant alterations in proteins related to synaptic function and inflammation. Notably, neurofilament light polypeptide, a biomarker for neurodegenerative diseases, was elevated in KIF5A ALS but not in SPG10 individuals. Moreover, these findings can now be used to gain mechanistic understanding of axonopathies linking to N- versus C-terminal KIF5A variants affecting both central and peripheral nervous systems.