Adult-Onset Neuronal Ceroid Lipofuscinosis: CLN5 Variant Presenting as Focal Dystonia

Neuronal ceroid lipofuscinosis (NCL) is a rare hereditary lysosomal storage disorder causing neuronal loss and progressive neurodegeneration. CLN variants cause varied phenotypic presentations.

A 49-year-old male presented with late adult-onset progressive focal right lower limb dystonia. Imaging showed cerebellar atrophy, and genetic testing was positive for the CLN5 variant (c.826T > C; p.Phe276 Leu) with uncertain significance. Skin biopsy suggested NCL, which made us consider the variant pathogenic, leading to novel phenotypic presentation.

Isolated focal dystonia has not been reported as an initial presentation in ANCL. Early genetic testing and periodic clinical assessments are advisable for better management and prognostication.