Chorea-acanthocytosis

What it is, symptoms and effects

From: MedlinePlus Genetics, National Library of Medicine

Chorea-acanthocytosis is primarily a neurological disorder that 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). This condition is one of a group of conditions called neuroacanthocytoses that involve neurological problems and abnormal red blood cells.

In addition to chorea, 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 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 in individuals with this condition, and can lead to an inability to speak.

Behavioral changes are 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.

Causes and biological mechanisms

From: MedlinePlus Genetics, National Library of Medicine

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.

Inheritance and family implications

From: MedlinePlus Genetics, National Library of Medicine

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.

How common is it?

From: MedlinePlus Genetics, National Library of Medicine

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

Reported clinical features and what the terms mean

The following findings are associated with this condition in Orphanet. They are not a checklist for diagnosing yourself, and they do not all occur in every affected person. Some are examination, imaging or laboratory findings that cannot be recognised at home.

The frequency labels describe how often a finding was reported among people with the condition in the source. They do not give the chance that a person with that symptom has the condition. Definitions below reproduce HPO terminology; they explain the term, not the likely severity in an individual.

Chorea · Very frequent (99-80%)

Chorea (Greek for 'dance') refers to widespread arrhythmic involuntary movements of a forcible, jerky and restless fashion. It is a random-appearing sequence of one or more discrete involuntary movements or movement fragments. Movements appear random because of variability in timing, duration or location. Each movement may have a distinct start and end. However, movements may be strung together and thus may appear to flow randomly from one muscle group to another. Chorea can involve the trunk, neck, face, tongue, and extremities.

Involuntary movements · Very frequent (99-80%)

Involuntary contractions of muscle leading to involuntary movements of extremities, neck, trunk, or face.

Abnormal erythrocyte enzyme activity · Frequent (79-30%)

An altered level of any enzyme to act as catalysts within erythrocytes. This term includes changes due to altered activity of an enzyme.

Absent Achilles reflex · Frequent (79-30%)

Absence of the Achilles reflex (also known as the ankle jerk reflex), which can normally be elicited by tapping the tendon is tapped while the foot is dorsiflexed.

Acanthocytosis · Frequent (79-30%)

Acanthocytosis is a type of poikilocytosis characterized by the presence of spikes on the cell surface. The cells have an irregular shape resembling many-pointed stars.

Atypical behavior · Frequent (79-30%)

Atypical behavior is an abnormality in a person's actions that can be controlled or modulated by the will of the individual. While abnormal behaviors can be difficult to control, they are distinct from other abnormal actions that cannot be affected by the individual's will.

Decreased amplitude of sensory action potentials · Frequent (79-30%)

A reduction in the amplitude of sensory nerve action potential. This feature is measured by nerve conduction studies.

Distal amyotrophy · Frequent (79-30%)

Muscular atrophy affecting muscles in the distal portions of the extremities.

Distal muscle weakness · Frequent (79-30%)

Reduced strength of the musculature of the distal extremities.

EMG: neuropathic changes · Frequent (79-30%)

The presence of characteristic findings of denervation on electromyography (fibrillations, positive sharp waves, and giant motor unit potentials).

Elevated circulating creatine kinase concentration · Frequent (79-30%)

The activity of creatine kinase in the blood circulation is above the upper limit of normal.

Impaired vibratory sensation · Frequent (79-30%)

A decrease in the ability to perceive vibration. Clinically, this is usually tested with a tuning fork which vibrates at 128 Hz and is applied to bony prominences such as the malleoli at the ankles or the metacarpal-phalangeal joints. There is a slow decay of vibration from the tuning fork. The degree of vibratory sense loss can be crudely estimated by counting the number of seconds that the examiner can perceive the vibration longer than the patient.

Laryngeal dystonia · Frequent (79-30%)

A form of focal dystonia that affects the vocal cords, associated with involuntary contractions of the vocal cords causing interruptions of speech and affecting the voice quality and often leading to patterned, repeated breaks in speech.

Limb dystonia · Frequent (79-30%)

A type of dystonia (abnormally increased muscular tone causing fixed abnormal postures) that affects muscles of the limbs.

Other findings in the same source

From: Orphanet

Additional reported features include Motor tics (Frequent (79-30%)); Myopathy (Frequent (79-30%)); Parkinsonism (Frequent (79-30%)); Peripheral axonal neuropathy (Frequent (79-30%)); Phonic tics (Frequent (79-30%)); Reduced tendon reflexes (Frequent (79-30%)); Seizure (Frequent (79-30%)); Square-wave jerks (Frequent (79-30%)); Caudate atrophy (Frequent (79-30%)); Falls (Frequent (79-30%)). This is a selected summary, not a complete description of the condition.

Which doctor should you see?

The suggested department for discussing Chorea-acanthocytosis is Neurology, with a neurologist as the relevant type of clinician. General physician / Family Medicine; paediatrician for children. Referral depends on symptoms.

Additional services that may be relevant, depending on the findings, include: Clinical Genetics.

This is an editorial referral starting point. The appropriate clinic depends on the person’s age, symptoms, previous diagnosis and local services. The first clinician can decide whether another specialty or a team is needed; a department label does not confirm the diagnosis.

How to prepare for an assessment

Bring a short timeline of the main symptoms: when they first appeared, whether they are constant or episodic, what seems to change them, and how they affect daily activities. Include previous reports, discharge summaries, current medicines and supplements, allergies, and any relevant family history. A dated record is more useful than trying to match every feature in an online article.

Ask the clinician what is already established and what remains uncertain. If a test is suggested, ask what question it answers, what its limitations are and how the result would change the next step. The information here is not an instruction to arrange every possible test. In children, bring growth, developmental and school information if it is relevant to the concern.

• Which nervous-system findings help explain the symptoms?
• Would an assessment of walking, communication or daily function be helpful?
• Are rehabilitation or other specialist services relevant?

Treatment discussions and follow-up

The material gathered for this draft does not provide a complete condition-specific treatment pathway for Chorea-acanthocytosis. That gap does not mean that treatment is unavailable. A clinician needs to establish the diagnosis and review current guidance before recommending medicines, procedures, rehabilitation or other support.

Before leaving the appointment, clarify the next review date, who will communicate results, and whom to contact if the situation changes. Discuss difficulties with sleep, work, school, mobility, eating or emotional wellbeing when these are relevant. Practical support may require coordination between the treating clinician and other services.

The collected references do not establish a complete prevention or long-term outlook section for this entry. Missing information should not be interpreted as proof that prevention is impossible or that a particular outcome is inevitable. Ask what is known for the exact subtype, stage and personal circumstances, and which uncertainties remain.

When to seek emergency help

Severe breathing difficulty, collapse, new stroke-like symptoms, a seizure that is prolonged or repeated without recovery, uncontrolled major bleeding, or an immediate risk of self-harm require emergency help. In India, call 112 or reach the nearest emergency department. This is a general, non-exhaustive warning list; it is not a condition-specific triage tool.