Chorea-acanthocytosis

Alternate names

Acanthocytosis with neurologic disorder; ChAc; Choreoacanthocytosis; Chorea acanthocytosis

Definition

Chorea-acanthocytosis is one of a group of conditions called the neuro acanthocytoses that involve neurological problems and abnormal red blood cells. The condition is characterized by involuntary jerking movements (chorea), abnormal star-shaped red blood cells (acanthocytosis), and involuntary tensing of various muscles (dystonia), such as those in the limbs, face, mouth, tongue, and throat.

Epiemiology

It is estimated that 500 to 1,000 people worldwide have chorea-acanthocytosis.

Cause

Mutations in the VPS13A gene cause chorea-acanthocytosis. The VPS13A gene provides instructions for producing a protein called chorein; the function of this protein in the body is unknown. Some researchers believe that chorein plays a role in the movement of proteins within cells.

Gene mutations

• Most VPS13A gene mutations lead to the production of an abnormally small, nonfunctional version of chorein.
• The VPS13A gene is active (expressed) throughout the body; it is unclear why mutations in this gene affect only the brain and red blood cells.

Inheritance

Autosomal recessive inheritance, a 25% chance

• This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations.
• The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.

Signs and symptoms

• Chorea-acanthocytosis affects movement in many parts of the body.
• Chorea refers to the involuntary jerking movements made by people with this disorder.
• People with this condition also have abnormal star-shaped red blood cells (acanthocytosis).
• Another common feature of chorea-acanthocytosis is involuntary tensing of various muscles (dystonia), such as those in the limbs, face, mouth, tongue, and throat.
• These muscle twitches can cause vocal tics (such as grunting), involuntary belching, and limb spasms.
• Eating can also be impaired as tongue and throat twitches can interfere with chewing and swallowing food.
• People with chorea-acanthocytosis may uncontrollably bite their tongue, lips, and inside of the mouth.
• Nearly half of all people with chorea-acanthocytosis have seizures.
• Individuals with chorea-acanthocytosis may develop difficulty processing, learning, and remembering information (cognitive impairment).
• They may also have reduced sensation and weakness in their arms and legs (peripheral neuropathy) and muscle weakness (myopathy).
• Impaired muscle and nerve functioning commonly cause speech difficulties, and can lead to an inability to speak.
• Behavioral changes are also a common feature of chorea-acanthocytosis and may be the first sign of this condition.
• These behavioral changes may include changes in personality, obsessive-compulsive disorder (OCD), lack of self-restraint, and the inability to take care of oneself.
• The signs and symptoms of chorea-acanthocytosis usually begin in early to mid-adulthood.
• The movement problems of this condition worsen with age.
• Loss of cells (atrophy) in certain brain regions is the major cause of the neurological problems seen in people with chorea-acanthocytosis.

Diagnosis

• The diagnosis of ChAc is based primarily on clinical findings, the presence of characteristic MRI findings, and evidence of muscle disease. [1].
• CT and MRI reveal atrophy of the caudate nuclei with dilatation of the anterior horns of the lateral ventricles. MRI commonly shows T2-weighted signal increase in the caudate and putamen.
• Acanthocytes are present in 5%-50% of the red cell population.
• In some cases, acanthocytosis may be absent or may appear only late in the course of the disease.
• Increased serum concentration of muscle creatine kinase (CK) is observed in the majority of affected individuals.
• Muscle biopsy reveals central nuclei and atrophic fibers.
• VPS13A, which encodes chorein, is the only gene in which mutation is currently known to cause ChAc.

Treatment

• There are currently no treatments to prevent or slow the progression of chorea-acanthocytosis; treatment is symptomatic and supportive.
• Management may include: botulinum toxin for decreasing the oro-facio-lingual dystonia
• Feeding assistance
• speech therapy
• Mechanical protective devices
• splints for foot drop
• phenytoin, clobazam, and valproate for seizure management
• Antidepressant or antipsychotic medications
• Dopamine antagonists such as atypical neuroleptics or tetrabenazine
• Standard treatment for cardiomyopathy. Surveillance includes monitoring of nutritional status and adaptation of diet to assure adequate caloric intake, cardiac evaluations every five years, and EEG every third year.

NIH genetic and rare disease info

• NIH info on Chorea-acanthocytosis

Chorea-acanthocytosis is a rare disease.

Chorea-acanthocytosis Resources
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