Pure Hereditary Spastic Paraplegia in a Patient With a Novel Heterozygous KIDINS220 Gene Mutation.

This case presents a somewhat unique and different phenotype of hereditary spastic paraplegia from previously reported kinase D-interacting substrate of 220 kDa (KIDINS220) gene mutation-related disease. We report a unique putative causative heterozygous mutation in KIDINS220 in a pure hereditary spastic paraplegia (HSP) patient expanding the HSP group further. We also deliberate on how our case was different from prior KIDINS220-related pathologies including spastic paraplegia, intellectual disability, nystagmus, and obesity (SINO) syndrome, and the observation of KIDINS220 and aquaporin-4 (AQP4) downregulation in the ventricular ependymal lining of idiopathic normal pressure hydrocephalus (iNPH) patients. These findings warrant further investigations of the biology of KIDINS220. With the advent of new gene editing technologies like Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/CRISPR-associated protein 9 (Cas9), variants such as ours provide an opportunity for targeted precision medicine.