Huntington’s disease (“Huntington’s chorea” or “Saint Guy’s dance”) is one of the most common hereditary neurological diseases. What is the cause ? How is it transmitted? How do we die?
There Huntington’s disease owes its name to George Huntington who first described it in 1872, in the United States. It is one of hereditary neurological diseases the most common: a affected parent has a 50% chance of transmitting the mutated gene to her child. There is no no treatment to cure or slow Huntington’s disease. Treatments support symptoms. Discovery with the Dr. Erwan Bezarddoctor in neuroscience and director of the Institute of Neurodegenerative Diseases in Bordeaux.
Definition: what is Huntington’s disease or chorea?
There Huntington’s disease (formerly called “Huttington’s chorea”and before that again “dance of Saint Vitus”) East a neurodegenerative disease of the central nervous system, hereditary and genetics which causes a number of motor, cognitive and psychiatric symptoms progressing to loss of autonomy and even death. Disease orphanits prevalence in the Western population is estimated according to the High Authority of Health at 4-10/100,000.
Causes and transmission of Huntington’s disease
Huntington’s disease is a genetic disease caused by a mutation in the gene coding for a protein called “huntingtin”. THE individuals carrying the mutation will necessarily develop the disease. A parent carrying the mutation has a 50% risk of transmitting the disease to their child.
What are the symptoms of Huntington’s disease?
Huntington’s disease most commonly occurs in the young adult (20-30 years old) although there may be early (juvenile) and late forms. “Symptoms in the form of cognitive alterations can appear very early in the disease. This can be relatively subtle things: a attention disorder, executive disorder – having trouble making decisions for example. It is not specific to Huntington’s disease, however.“. Gradually, all the patient’s motor functions deteriorate until it becomes impossible to perform certain gestures, to move around alone, to eat or even to communicate. THE huntington disease symptoms are :
- chorea: abnormal, involuntary, spontaneous, uncontrollable, irregular, intermittent, unrhythmic and aimless movements, affecting the trunk, face and limbs (worse by fatigue, stress).
- dystonias (cramps and abnormal postures)
- coordination disorders,
- slowing of movements,
- muscle rigidity
- akathisia : syndrome characterized by unpleasant feelings of “inner” agitation which manifests itself by inability to sit still.
- swallowing disorders
- myoclonus (sudden, brief, involuntary muscle contractions)
- gait and balance disorders
- bruxism (involuntary clenching of the teeth (grinding), contraction of the jaw)
- cognitive deficits
- language and attention disorders
- memory problems
- disorientation in space
- psychiatric symptoms (depression, anxiety, irritability, aggressiveness, psychosis, obsessions, suicidal risk)
- personality disorders (impulsivity, impatience, inflexibility, psychorigidity…).
- psychotic states with delusions, hallucinations, obsessions
- sleeping troubles
- weightloss
Diagnosis: genetic test for Huntington’s disease
The diagnosis of Huntington’s disease is based on clinical examinations when faced with a patient presenting with disorders suggestive of the disease and according to the family context. It’s the genetic test that will clarify the diagnosis. Very often, the genetic test will be carried out before any symptoms appear. Indeed, as Dr. Bezard points out, “Families carrying the gene are most often known and followed up in genetic consultation centres.“ The diagnosis is established by a geneticist who will make the announcement of the disease. Support will be established in centers of abnormal movements.
What are the treatments for Huntington’s disease?
There is no no cure for Huntington’s disease. “Todaytreatments are exclusively symptomatic and non-specifics, says Dr. Bezard. This is’improve the patient’s quality of life. There is no treatment for the disease itself although research is progressing, in particular to slow the progression of huntingtin protein aggregation, to slow the loss of neurons. Neuron transplantation is also a track“. The symptomatic management of Huntington’s disease is multi-disciplinary:
- Drug treatments can relieve psychiatric disorders (antidepressants, anxiolytics, etc.) but also choreic movements (dopamine stabilizers, neuroleptics, etc.)
- Non-drug treatments go through physical rehabilitation with a physiotherapist, speech therapy sessions and regular physical activity.
Accompanying measures in daily life are essential to respond to the loss of autonomy.
What is the life expectancy of Huntington’s disease?
Huntington’s disease is an incurable disease. After the first symptoms, the average duration of the disease is 15-20 years, but this duration varies according to the individual.
Most people with do not die directly from the disease, but rather from clinical disorders which result from the weakening of the management of the organism by the brain, in particular following “false roads”, infectious disorders (pneumopathies for example) or cardiovascular disorders.
Can Huntington’s disease be prevented?
Before design“prevention is based on genetic testing and informing the carrier“ explains Dr. Bezard. He can knowingly choose to take the risk of procreating or not. After conception, two types of diagnosis are possible:
► Prenatal diagnosis which consists of looking for a mutation in the huntingtin gene in a fetus during pregnancy. This test is carried out if one of the parents is a carrier of this anomaly. In the event of a positive result, the couple can choose to terminate the pregnancy at any time.
►Preimplantation diagnosis for parents who have recourse to in vitro fertilization (IVF) if one of the parents is a carrier of the mutation or if one of the grandparents is affected by the disease. The technique then consists in looking for the genetic anomaly on the embryos obtained by IVF, three days after fertilization, and in selecting one or two healthy embryos to be transferred into the mother’s uterus.
Associations for Huntington’s disease
Association Huntington France (AHF)
A Rainbow for Huntington’s patients
Thanks to Doctor Erwan Bezard, doctor in neuroscience and director of the Institute of Neurodegenerative Diseases in Bordeaux.
Source: National Protocol for Diagnosis and Care (PNDS) Huntington’s disease, Haute Autorité de Santé, September 2021.