Chorea-acanthocytosis

Chorea-acanthocytosis 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.

Chorea-acanthocytosis is one of a group of conditions called the neuroacanthocytoses 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. Chorea-acanthocytosis is caused by mutations in the VPS13A gene and is inherited in an autosomal recessive manner. There are currently no treatments to prevent or slow the progression of chorea-acanthocytosis; treatment is symptomatic and supportive.

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. 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.

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; and 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.