Hereditary neurodegenerative diseases have a huge impact on the lives of the people who suffer from them and the people around them, since they usually have no cure and are characterized by emotionally painful psychiatric and mental symptoms. One of the most severe that we know of is Huntington’s disease.
What is Huntington’s disease? What are your causes?
Huntington’s disease is a rare inherited degenerative disease that affects the basal ganglia, a part of the brain that is mostly responsible for controlling movement. Its progression is very slow (usually during a period ranging from 15 to 20 years) and is characterized by the progressive appearance of movement and psychiatric disorders.
It affects men and women equally and has an approximate incidence of between 5 and 10 affected per 100,000 inhabitants. It is more common in people of European descent, while people of Asian or African origin are less likely to suffer from it.
Its origin is in a mutation on chromosome 4, in which there is an expansion of triplets (DNA sequences of three molecules) CAG (Cytosine-Adenine-Guanine). While in a healthy chromosome this sequence is repeated 34 times, in an altered chromosome it is repeated more than 40; the more, the more severe the symptoms and the sooner they will appear.
With Huntington’s disease, as with other degenerative diseases caused by triplet expansions, there is a phenomenon known as gene anticipation : the number of repetitions tends to increase with the generations, with which the disease becomes more and more aggressive and begins its course at an earlier age.
Their autosomal inheritance is dominant , so the descendants of a person with Huntington’s disease have a 50% chance of receiving the mutation.
What are your symptoms?
The symptoms of Huntington’s disease usually appear between 30 and 50 years of age , which has traditionally favored its perpetuation since it was common for most people who suffered from it to have offspring at the time of discovery. If they appear before the age of 20, it is called juvenile Huntington’s disease.
Usually the first symptoms to appear are psychiatric , and the most common of them are recurrent depressive disorders; however, it can also take the form of obsessive compulsive disorder, mania, or bipolar disorder. These disorders tend to worsen and often lead to psychosocial deterioration due to the damage they generate in the patient’s environment, as well as the tendency they cause to impulsive behaviors (for example, risky sexual behaviors and hypersexual aggressiveness). As the condition progresses, cognitive function may be compromised with memory loss, difficulty maintaining concentration, and speech disorders.
Along with them, there are also movement disorders consisting of involuntary jerking or contortion movements, muscle problems, slow or abnormal eye movements, impaired balance and difficulty swallowing.
Over time, the patient ends up bedridden, unable to move or speak, although it is common for them to continue to recognize family and friends. Ultimately, Huntington’s disease leads to death.
How is it treated?
Huntington’s disease has no known cure and almost inevitably leads to death. However, there are many strategies that can significantly alleviate or delay symptoms.
Thus, there are pharmacological treatments with neuroleptics, dopamine blockers and others that reduce the severity of movement disorders ; and associated psychiatric disorders can be treated in a similar way to when they are idiopathic (with pharmacology, psychotherapy, family therapy, occupational …).
On the other hand, there is ongoing research with various drugs that appear to have significant potential in slowing down the disease, and gene therapy appears equally promising, although all of these treatments are not yet available for use in humans.
Finally, the possibility of diagnosing the disease prenatally , when there is a family history, allows people who suffer from it (or believe they can suffer it but do not want to know their own case) to opt for assisted reproductive techniques that prevent the birth of children with the disease. However, this is a rare option; Among other issues, it is common that couples in which a member suffers from this disease do not wish to have children to prevent the degeneration of the affected person from coinciding with the growth of the child.