Neuroacanthocytosis is a heterogeneous group of genetic disorders that predominantly affects the basal ganglia and is characterized by abnormal movements and acanthocytes on peripheral blood smear. Symptoms may vary depending on the exact disease, but they commonly include chorea, dystonia, orofacial dyskinesias with tongue protrusion and lip biting, tics, dysarthria, parkinsonism, walking abnormalities, axonal neuropathy, cognitive decline, and psychiatric or behavioral problems. Patients may also develop seizures.

Neuroacanthocytosis syndromes may be classified into 2 main categories:

• Core syndromes (ie, McLeod syndrome, chorea-acanthocytosis syndrome)
• Diseases of abnormal lipoprotein metabolism (ie, abetalipoproteinemia)

McLeod syndrome is an X-linked disorder. It presents between the third and seventh decade of life and has a slowly progressive course. Psychiatric symptoms may precede abnormal movements by years. Chorea can be the presenting neurologic symptom, but other abnormal movements may also develop. Unlike chorea-acanthocytosis syndrome, orofaciolingual dystonia is uncommon. An axonal neuropathy and a myopathy often develop. Cardiomyopathy occurs in the majority of patients and is a common cause of death.

Chorea-acanthocytosis syndrome is an autosomal recessive disorder. It presents in the third decade of life and has a slowly progressive course over 15-30 years. Psychiatric symptoms and subtle cognitive changes often occur years prior to abnormal movements. Abnormal movements include chorea, orofaciolingual dystonia (leading to feeding difficulties), limb dystonia, and sometimes parkinsonism. Axonal neuropathy and myopathy may occur but are often mild. Cardiac disease typically does not occur. However, sudden unexplained deaths have been reported.

Abetalipoproteinemia is an autosomal recessive disorder. It typically presents in infancy and, if untreated, symptoms progress over time. With appropriate treatment, patients can live into adulthood with minimal symptoms. Initial symptoms include failure to thrive, diarrhea, and vomiting. Acanthocytes are often present and lead to a hemolytic anemia and hyperbilirubinemia. Malabsorption of fat-soluble vitamins can lead to increased bleeding. Untreated children eventually develop pigmentation of the retina (which may lead to vision loss) and a neuropathy (which may lead to a sensory ataxia).

These disorders are rare but may also be underdiagnosed. Each disorder is estimated to affect approximately 1-5 per million people worldwide.