Progressive ataxia and orolingual chorea revealing a novel VPS13A variant: a case report of chorea-acanthocytosis without peripheral acanthocytosis with a literature review.

Chorea-acanthocytosis (ChAc), also referred to as VPS13A-related disease, is a rare autosomal recessive neurodegenerative disorder caused by biallelic pathogenic variants in VPS13A. Peripheral acanthocytosis, historically considered a diagnostic hallmark, is increasingly recognized as variable and inconsistent. We describe a 47-year-old Moroccan man presenting with progressive gait instability, orolingual chorea, dysarthria, dysphagia, elevated serum creatine kinase, and axonal sensorimotor neuropathy. Repeated peripheral blood smears failed to demonstrate acanthocytosis. Brain MRI showed bilateral caudate and lentiform nucleus atrophy associated with mild non-specific midbrain atrophy. Exome sequencing identified a homozygous pathogenic VPS13A variant: NM_033305.3.3164dupT (p.Leu1055PhefsTer4). The variant was confirmed by Sanger sequencing and classified as pathogenic according to ACMG criteria (Class 5). This report expands the mutational spectrum of VPS13A-related disease and highlights the importance of integrating molecular genetics with clinical and neuroradiological findings for accurate diagnosis, particularly in the absence of peripheral acanthocytosis.