Huntington’s disease is often diagnosed around age 30.
Huntington’s disease, formerly called “Saint Guy’s Dance”, owes its name to George Huntington who first described it in 1872 in the United States. It is one of the most common hereditary neurological diseases: an affected parent has a 50% risk of transmitting the mutated gene to their child. It most often appears in young adults around the age of 30, although there can be early (juvenile) and late forms.
Definition: what is Huntington’s disease or chorea?
Huntington’s disease (“Huttington chorea” or “Saint Guy’s dance”) is a hereditary and genetic neurodegenerative disease of the central nervous system that causes a certain number of motor, cognitive and psychiatric symptoms progressing towards a loss of autonomy and until death. It is caused by a mutation in the gene coding for a protein called “Huntingtin”. The mutant Huntingtin protein exhibits toxic properties that lead to neuron dysfunction and death. Individuals carrying the mutation develop the disease. Its prevalence is estimated at 4-10 births per 100,000, according to the High Authority of Health.
What are the symptoms of Huntington’s disease?
The disease is characterized by progressive motor, cognitive and psychiatric disorders. “Symptoms in the form of cognitive alterations can appear very early in the disease. This can be relatively subtle things: an attention disorder, an executive disorder – having difficulty making decisions for example. This is not specific to Huntington’s disease, however.” explains Dr Erwan Bezard, doctor in neuroscience and director of the Bordeaux Institute of Neurodegenerative Diseases.
Among motor disorders, the most characteristic symptom is “chorea”. It is not present in all patients but when it is the case, it is characterized by the occurrence of excessive, unpredictable and irregular spontaneous movements. It can result in a simple exaggeration of gestures and expression, continuous movements of the hands, an unstable and dancing walk. The patient may also present movement abnormalities such as dystonia (abnormal tonic postures), rigidity, bradykinesia (slowness in initiating movements), gait and balance disorders up to loss of mobility. ambulation ability. Swallowing disorders leading to aspiration are also possible.
Psychiatric disorders may include depression and anxiety, manic states, delusions and more rarely hallucinations (less than 1%). Character disorders and personality changes often occur during the illness marked by irritability, aggressiveness and apathy. Apathetic patients may spend hours watching television and refuse any activity. Patients may also present with obsessions leading to obsessive-compulsive disorders.
Diagnosis: Genetic testing for Huntington’s disease
The diagnosis of Huntington’s disease is based on clinical examinations in a patient presenting disorders suggestive of the disease and according to the family context. It is the genetic test that clarifies the diagnosis. Very often, the genetic test is carried out before symptoms appear. As Dr. Bezard explains to us “families carrying the gene are most often known and followed in genetic consultation centers.” The diagnosis is established by a geneticist who will announce the disease. Support will be provided in abnormal movement centers.
What are the treatments for Huntington’s disease?
There is no cure for Huntington’s disease. “Today, treatments are exclusively symptomatic and not specific.s, explains Dr. Bezard. This is about improving the patient’s quality of life. There is no treatment for the disease itself even if research is progressing, in particular to slow down the progression of the aggregation of huntingtin protein, to slow down the loss of neurons. Neuron transplantation is also an avenue“. The symptomatic management of Huntington’s disease is multi-disciplinary:
- Drug treatments help 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.
Supportive measures in daily life are essential to respond to the loss of autonomy.
What is the life expectancy for Huntington’s disease?
Death can occur on average around twenty years after the onset of symptoms, but this duration varies depending on the individual. Most people affected do not die directly from the disease, but rather from clinical disorders which result from the weakening of the management of the body by the brain, in particular following “wrong paths”, infectious disorders (pneumopathies for example) or cardiovascular disorders.
Can Huntington’s disease be prevented?
Before pregnancy, “prevention is based on genetic testing and carrier information” explains Dr. Bezard. He will be able to knowingly choose whether 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 has 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 resort to in vitro fertilization (IVF) if one of the parents carries the mutation or if one of the grandparents is affected by the disease. The technique then consists of searching for the genetic anomaly on the embryos obtained by IVF, three days after fertilization, and selecting one or two healthy embryos to transfer into the mother’s uterus.
Thanks to Doctor Erwan Bezard, doctor in neuroscience and director of the Bordeaux Institute of Neurodegenerative Diseases.
- National Diagnostic and Care Protocol (PNDS) Huntington’s Disease, High Authority of Health, September 2021.
