Homozygous VPS13A Splice‐Site Variant Causing Chorea‐Acanthocytosis With Feeding Dystonia and Rubber‐Man Gait

Introduction Chorea‐acanthocytosis (ChAc), also increasingly termed VPS13A disease, is a very rare autosomal recessive neuroacanthocytosis syndrome caused by biallelic loss‐of‐function mutations in VPS13A . It is characterized by progressive chorea, orofacial dystonia, myopathy, and red‐cell acanthocytosis, and is frequently misdiagnosed as McLeod syndrome, Huntington disease, or Wilson disease because of overlapping phenomenology. Case Report We describe a 40‐year‐old man, born of non‐consanguineous parents, with an 18‐month history of progressive generalized chorea, truncal and limb dystonia, and disabling orolingual dyskinesia causing dysarthria, sialorrhea, tongue‐biting, and food‐bolus expulsion. Examination revealed cachexia, preserved cognition, and a characteristic stutter‐step “rubber‐man” gait. Serum creatine kinase was elevated at 650 U/L; Wilson disease workup was unremarkable. Peripheral smear showed acanthocytes, and MRI brain demonstrated bilateral caudate head atrophy with ex‐vacuo dilatation of the frontal horns. Whole‐exome sequencing identified a homozygous likely pathogenic splice‐donor variant, VPS13A c.3812+1G>T (intron 33), with no pathogenic variant identified in XK ; together with the phenotype, this biallelic finding strongly supported a diagnosis of VPS13A disease (chorea‐acanthocytosis) rather than XK disease (McLeod syndrome). Tetrabenazine paradoxically worsened dystonia; levodopa‐carbidopa gave partial relief, and gastrostomy was planned for feeding dystonia. Conclusion ChAc should be suspected in adults with generalized chorea, feeding dystonia, involuntary vocalizations, and a rubber‐man gait, particularly with elevated creatine kinase. Genetic testing remains the diagnostic gold standard, since acanthocytosis and imaging findings are variably expressed.