In a young adult with chorea and acanthocytes on blood smear, include chorea-acanthocytosis in the differential and arrange an EMG and brain MRI, because the neurogenic denervation pattern and caudate-putamen atrophy closely mimic Huntington disease. When a middle-aged man from an affected family develops progressive ataxia, tremor, and mild parkinsonism, obtain fragile X premutation testing before attributing the syndrome to a more common degenerative cause.

Presents with prominent chorea and severe orofacial dyskinesias, eventually progressing into a Huntington-like syndrome; Distinct disorder that typically manifests in an individual's second or third decade of life; Beyond the movement abnormalities, individuals can experience significant seizures, along with progressive muscle weakness and wasting that predominantly impacts their lower extremities; Evaluation relies on a peripheral blood smear to look for acanthocytes, which occurs alongside a completely normal lipid profile; HARP is an acronym that stands for hypoprebetalipoproteinemia, acanthocytosis, retinitis pigmentosa, and progressive pallidal degeneration