Neuroacanthocytosis Syndromes is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.
Neuroacanthocytosis (NA) syndromes are a group of rare, genetically heterogeneous neurodegenerative disorders characterized by the combination of progressive basal ganglia degeneration and acanthocytosis (misshapen, spiculated red blood cells) 1(https://www.ncbi.nlm.nih.gov/books/NBK560767/). The two core conditions in this group are chorea-acanthocytosis (ChAc, also known as VPS13A disease) and McLeod syndrome (MLS), which share clinical features of movement disorders, cognitive decline, psychiatric symptoms, and peripheral neuropathy but differ in their genetic basis, inheritance pattern, and multi-system involvement 2(https://rarediseases.org/rare-/diseases/neuroacanthocytosis/).
These disorders are classified among the basal ganglia degenerations and share pathological features with [Huntington's disease[/mechanisms/[huntington-pathway[/mechanisms/[huntington-pathway[/mechanisms/[huntington-pathway--TEMP--/mechanisms)--FIX--, including progressive striatal atrophy and movement disorders. However, the additional presence of acanthocytosis in peripheral blood provides an important diagnostic clue 3(https://www.ninds.nih.gov/health-information/disorders/neuroacanthocytosis). The neuroacanthocytosis syndromes belong to a broader category of conditions where acanthocytosis co-occurs with neurological disease, which also includes [pantothenate kinase-associated neurodegeneration (PKAN)[/diseases/[pantothenate-kinase-associated-neurodegeneration-pkan[/diseases/[pantothenate-kinase-associated-neurodegeneration-pkan[/diseases/[pantothenate-kinase-associated-neurodegeneration-pkan--TEMP--/diseases)--FIX-- and abetalipoproteinemia (Bassen-Kornzweig syndrome) 4(https://pmc.ncbi.nlm.nih.gov/articles/PMC3212896/).
| Syndrome |
Gene |
Inheritance |
Prevalence |
Key Features |
| Chorea-Acanthocytosis (ChAc) |
VPS13A |
Autosomal recessive |
~1:1,000,000 |
Orofacial dyskinesia, self-mutilation, seizures |
| McLeod Syndrome (MLS) |
XK |
X-linked recessive |
~1:10,000,000 |
Cardiomyopathy, hemolytic anemia, Kell antigen abnormalities |
- [Neurodegeneration with Brain Iron Accumulation (NBIA/PKAN)[/diseases/[neurodegeneration-brain-iron-accumulation[/diseases/[neurodegeneration-brain-iron-accumulation[/diseases/[neurodegeneration-brain-iron-accumulation--TEMP--/diseases)--FIX--: Pantothenate kinase-2 mutations; iron deposition in basal ganglia
- Abetalipoproteinemia (Bassen-Kornzweig syndrome): MTP gene mutations; fat malabsorption, neuropathy, retinopathy
- [Huntington's disease[/mechanisms/[huntington-pathway[/mechanisms/[huntington-pathway[/mechanisms/[huntington-pathway--TEMP--/mechanisms)--FIX---Like 2 (HDL2): JPH3 gene; clinically resembles HD with acanthocytosis
Chorea-acanthocytosis is caused by biallelic pathogenic variants in the VPS13A gene (previously known as CHAC) on chromosome 9q21 5(https://www.ncbi.nlm.nih.gov/books/NBK1387/). The VPS13A gene encodes chorein, a large protein of 3,174 amino acids involved in intracellular lipid transport and membrane dynamics. Over 150 pathogenic variants have been identified, including missense mutations, nonsense mutations, splice site mutations, and large deletions 6(https://www.frontiersin.org/journals/aging-neuroscience/articles/10.3389/fnagi.2017.00095/full).
Key genetic features:
- Autosomal recessive inheritance
- Complete loss of chorein protein in most cases (confirmed by Western blot)
- No clear genotype-phenotype correlation; clinical variability exists even within families
- VPS13A belongs to the VPS13 protein family (VPS13A-D), all involved in lipid transfer at membrane contact sites 7(https://www.ncbi.nlm.nih.gov/books/NBK1387/)
VPS13A/chorein functions in intracellular lipid trafficking at membrane contact sites between organelles 8(https://www.sciencedirect.com/science/article/pii/S0969996123003078):
- Lipid transfer: VPS13A mediates non-vesicular lipid transport between the endoplasmic reticulum and other organelles
- Actin cytoskeleton regulation: Chorein interacts with the actin cytoskeleton and band 3 protein in erythrocytes; loss leads to acanthocyte formation
- [autophagy[/entities/[autophagy[/entities/[autophagy[/entities/[autophagy--TEMP--/entities)--FIX-- regulation: VPS13A deficiency impairs [autophagy[/entities/[autophagy[/entities/[autophagy[/entities/[autophagy--TEMP--/entities)--FIX-- and [lysosomal] function
- Synaptic dysfunction: Mouse models show impaired corticostriatal [synaptic plasticity[/entities/[long-term-potentiation[/entities/[long-term-potentiation[/entities/[long-term-potentiation--TEMP--/entities)--FIX--, particularly loss of long-term depression (LTD) 9(https://www.sciencedirect.com/science/article/pii/S0969996123003078)
- neuroinflammation: VPS13A knockdown triggers [microglial[/https://www.sciencedirect.com/science/article/pii/[S0969996123003078[/https://www.sciencedirect.com/science/article/pii/[S0969996123003078[/https://www.sciencedirect.com/science/article/pii/[S0969996123003078--TEMP--/https://www.sciencedirect.com/science/article)--FIX--
- Dopaminergic dysfunction: Loss of dopaminergic nigrostriatal projections and [dopamine[/entities/[dopamine[/entities/[dopamine[/entities/[dopamine--TEMP--/entities)--FIX-- transporter binding, contributing to movement disorders
Age of onset: Typically 25-45 years (mean ~30 years) 11(https://www.ncbi.nlm.nih.gov/books/NBK1387/)
Movement Disorders:
- Chorea (involuntary jerky movements), often progressive
- Orofacial dyskinesia (lip and tongue dystonia) -- highly characteristic
- Involuntary tongue protrusion with feeding difficulties
- Habitual tongue and lip biting leading to self-mutilation -- pathognomonic finding
- Dystonia (generalized or focal)
- Tics and vocalizations
- Parkinsonism (rigidity, bradykinesia) may develop later
Psychiatric and Cognitive Features:
- Personality changes, apathy, depression
- Obsessive-compulsive behaviors
- Impulsive and disinhibited behavior (frontal lobe type)
- Progressive cognitive decline
- Psychosis in some patients
Neurological Features:
- Seizures (present in ~50% of patients; may be the presenting symptom)
- Peripheral neuropathy (sensorimotor axonal type)
- Areflexia
- Muscle weakness and atrophy (distal > proximal)
- Elevated creatine kinase (CK) levels
- Dysphagia and feeding difficulties
Disease Course:
- Chronic progressive, with major disability developing within years
- Mean survival approximately 10-20 years from onset
- Death often from aspiration pneumonia, complications of immobility, or sudden cardiac events
Characteristic neuropathological findings include 12(https://www.ncbi.nlm.nih.gov/books/NBK1387/):
- Striatal atrophy: Marked atrophy of the caudate nucleus (dorsal > ventral gradient) and putamen (caudal > rostral pattern)
- Neuronal loss: Predominantly medium spiny [neurons[/entities/[neurons[/entities/[neurons[/entities/[neurons--TEMP--/entities)--FIX-- in the striatum
- Gliosis: Reactive [astrocytosis] in the striatum
- Globus pallidus involvement: Variable neuronal loss and gliosis
- Substantia nigra: Dopaminergic neuron loss with reduced melanin
- Iron deposition: Variable iron accumulation in basal ganglia (distinguishes from [NBIA[/diseases/[nbia[/diseases/[nbia[/diseases/[nbia--TEMP--/diseases)--FIX-- where iron deposition is more pronounced)
- Peripheral nerve: Chronic axonal neuropathy with nerve fiber loss
MRI findings include 13(https://www.ncbi.nlm.nih.gov/books/NBK1387/):
- Bilateral caudate nucleus atrophy with ventricular dilatation
- Putaminal atrophy
- Variable cortical atrophy
- Increased T2 signal in the caudate and putamen (in some cases)
- Hippocampal atrophy and sclerosis (reported in some patients)
- DaTscan/PET: Reduced striatal [dopamine[/entities/[dopamine[/entities/[dopamine[/entities/[dopamine--TEMP--/entities)--FIX-- transporter binding
Age of onset: Typically 40-60 years (later than ChAc) 15(https://www.ncbi.nlm.nih.gov/books/NBK1354/)
Hematological Features:
- Acanthocytosis (present in virtually all patients)
- Weak Kell antigen expression (McLeod blood phenotype)
- Compensated hemolytic anemia with reticulocytosis
- Transfusion risk: Patients can develop severe alloantibodies against Kell antigens, making transfusion hazardous
Movement Disorders:
- Chorea (often milder than ChAc)
- Dystonia
- Tics and vocalizations
- Orofacial dyskinesia (less prominent than ChAc)
- Parkinsonism in later stages
Cardiac Involvement:
- Dilated cardiomyopathy (major cause of morbidity and mortality)
- Atrial fibrillation
- Tachyarrhythmias
- Cardiac monitoring essential throughout disease course
Neuromuscular Involvement:
- Sensorimotor axonal neuropathy
- Myopathy with elevated CK
- Muscle weakness and wasting
Psychiatric and Cognitive Features:
- Personality changes
- Depression and anxiety
- Cognitive decline
- Psychosis (rare)
Disease Course:
- Slowly progressive over decades
- Cardiac complications are the leading cause of death
- Mean age at death approximately 55-65 years
Acanthocyte identification is essential but technically challenging 16(https://www.ncbi.nlm.nih.gov/books/NBK560767/):
- Fresh wet blood film: Most sensitive method; use phase-contrast microscopy
- Dilution in saline: 1:1 dilution with normal saline, examining within 30 minutes
- Percentage: Usually 5-50% of red blood cells appear as acanthocytes
- False negatives: Common with standard Wright-stained smears; fresh preparations essential
- Automated blood count may show elevated MCHC or abnormal red cell distribution width
- ChAc: VPS13A gene sequencing; Western blot for chorein protein (absent in >95% of cases)
- MLS: XK gene sequencing; Kell antigen phenotyping on red blood cells
- Elevated CK: Present in both ChAc and MLS (often 300-3000 U/L)
- Liver enzymes: May be mildly elevated
- Lipid profile: Normal (distinguishes from abetalipoproteinemia)
- Kell phenotype: Weak Kx/Kell expression in MLS; normal in ChAc
- MRI: Caudate and putaminal atrophy (more pronounced in ChAc than MLS)
- DaTscan: Reduced striatal [dopamine[/entities/[dopamine[/entities/[dopamine[/entities/[dopamine--TEMP--/entities)--FIX-- transporter binding
- FDG-PET: Hypometabolism in the basal ganglia
- Echocardiography: Screening for dilated cardiomyopathy
- ECG: Arrhythmia detection
- Holter monitoring: 24-hour rhythm surveillance
- Cardiac MRI: For detailed structural assessment
No disease-modifying therapies currently exist for neuroacanthocytosis syndromes 17(https://rarediseases.org/rare-/diseases/neuroacanthocytosis/). Management is symptomatic:
Movement Disorder Management:
- Tetrabenazine or valbenazine for chorea
- Botulinum toxin injections for focal dystonia (especially orofacial)
- [dopamine[/entities/[dopamine[/entities/[dopamine[/entities/[dopamine--TEMP--/entities)--FIX-- agonists for parkinsonism
- Dental guards and protective measures for self-mutilation
Seizure Management:
- Anticonvulsant therapy (levetiracetam, valproic acid, carbamazepine)
- Seizures in ChAc often respond to standard anticonvulsants
Psychiatric Management:
- Antidepressants (SSRIs preferred)
- Atypical antipsychotics for psychosis or severe behavioral disturbance (with caution, as they may worsen movement disorders)
- Behavioral interventions
Cardiac Management (MLS):
- Regular cardiac surveillance
- Standard heart failure therapy for cardiomyopathy
- Antiarrhythmic agents as needed
- Pacemaker or defibrillator implantation in select cases
Transfusion Considerations (MLS):
- McLeod phenotype red blood cells required for safe transfusion
- Autologous blood banking recommended before elective procedures
- National rare blood registries should be consulted
Supportive Care:
- Physical and occupational therapy
- Speech therapy for dysphagia and dysarthria
- Nutritional support
- Genetic counseling for families
- [Deep brain stimulation (DBS)[/treatments/[deep-brain-stimulation[/treatments/[deep-brain-stimulation[/treatments/[deep-brain-stimulation--TEMP--/treatments)--FIX-- of the globus pallidus internus (GPi) has been reported in several ChAc cases
- Some improvement in chorea and dystonia
- Variable and sometimes transient benefit
- Should be considered in medically refractory cases 18(https://www.e-jmd.org/journal/view.php?number=129)
- Lithium: Has shown neuroprotective effects in ChAc cellular models by enhancing [autophagy[/entities/[autophagy[/entities/[autophagy[/entities/[autophagy--TEMP--/entities)--FIX--
- VPS13A gene therapy: Preclinical investigations exploring [AAV-based gene delivery[/treatments/[gene-therapy[/treatments/[gene-therapy[/treatments/[gene-therapy--TEMP--/treatments)--FIX--
- Red blood cell lipid research: 2025 studies on lipid distribution abnormalities in ChAc and MLS erythrocytes may yield biomarker and therapeutic insights 19(https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2025.1543812/full)
- Stem cell approaches: Early preclinical investigations for neuronal replacement
The neuroacanthocytosis syndromes share features with several other neurodegenerative conditions:
- [Huntington's disease[/mechanisms/[huntington-pathway[/mechanisms/[huntington-pathway[/mechanisms/[huntington-pathway--TEMP--/mechanisms)--FIX--: Similar striatal degeneration, chorea, psychiatric symptoms, and cognitive decline; HD lacks acanthocytosis and peripheral neuropathy
- [Neurodegeneration with Brain Iron Accumulation (NBIA)[/diseases/[neurodegeneration-brain-iron-accumulation[/diseases/[neurodegeneration-brain-iron-accumulation[/diseases/[neurodegeneration-brain-iron-accumulation--TEMP--/diseases)--FIX--: Overlapping basal ganglia degeneration; NBIA features prominent iron deposition
- [Parkinson's disease[/diseases/[parkinsons[/diseases/[parkinsons[/diseases/[parkinsons--TEMP--/diseases)--FIX--: Dopaminergic dysfunction is shared, though the pattern differs
- [frontotemporal dementia[/diseases/[ftd[/diseases/[ftd[/diseases/[ftd--TEMP--/diseases)--FIX--: Behavioral and personality changes similar to the frontal lobe syndrome in ChAc
- [Wilson's Disease[/diseases/[wilson-disease[/diseases/[wilson-disease[/diseases/[wilson-disease--TEMP--/diseases)--FIX--: Another treatable cause of basal ganglia degeneration with psychiatric features
The study of Neuroacanthocytosis Syndromes has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.
Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.
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- [Untangling the Thorns: Advances in the Neuroacanthocytosis Syndromes. J Mov Disord. Link)
- [Red blood cell lipid distribution in chorea-acanthocytosis and McLeod syndrome patients. Front Physiol. 2025. Link)