Juvenile Huntington’s Disease is a neurodegenerative disorder that causes erratic movements and cognitive and behavioral disturbances.
It is a disease that affects patients of 20 years old or younger. It is a rare condition, and it involves around 5% of all patients with Huntington’s Disease. Within this article, you will find answers to some of the most common questions like what it is, at what age the symptoms start, and many others. Before reaching that point, there will be brief explanations about the basic concepts of the disease.
By reading this article, you will obtain critical insights about Juvenile Huntington’s disease, how does it happens, its signs and symptoms, and its treatment. Please continue reading to get pearls on this specific topic by the hand of a doctor.
What is juvenile Huntington’s disease?
In order to define Juvenile Huntington’s disease, it is essential to know what Huntington’s disease is. Both of them are the same condition; the only difference is that one has a juvenile-onset. The other has an adult-onset.
Huntington’s disease is an inherited disease that causes the continuous malfunction or degeneration of nerve cells in the brain. It occurs due to Cytosine, Adenine, and Guanine (CAG) trinucleotide repeat on chromosome 4.
There are 23 pairs of chromosomes on our genetic code. This alteration affects the Huntingtin gene or HTT gene directly. This causes a mutation within the brain that leads to neuronal degeneration. However, the CAG repeat length will determine how severe the disease will be and how early the symptoms will develop.
The CAG repeat on adults is on the range of 36 to 55 repetitions, while juvenile cases have repetitions over 60.
Now Juvenile onset Huntington’s disease is the same as Huntington’s disease, but the number of repetitions is greater. This talks about the severity of the disease and how quickly the symptoms will begin.
Juvenile HD patients have slightly different symptoms than adult-onset Huntington’s disease. The hallmark of Huntington’s Disease is Huntington’s chorea, which is mild or not even present in juvenile-onset HD.
Chorea refers to a movement disorder that causes involuntary and unpredictable body movements. Nonetheless, these patients tend to develop seizures making this condition more severe.
Is Huntington’s disease a form of dementia?
Yes, although Huntington’s disease is thought of as only to have movement or motor symptoms, it can present mental or cognitive symptoms as well.
The disease progression leads to a cognitive impairment that ultimately becomes a form of dementia. It affects the JHD patient and the HD patient as well.
The patients will develop psychiatric symptoms and mental symptoms like mood swings, irritability, behavioral changes, and cognitive impairment. This disease causes a decline in thinking and reasoning skills, including memory, concentration, judgment, and ability to plan and organize.
The brain disorder caused by the HD gene leads to several alterations. Among these alterations, there are neuronal aggregates that contain the mutant HTT causing impairments.
A change in the nerve impulse can also happen among the nerve cells leading to erratic responses. Similarly, this may lead to unpredictable activities in the brain and cause cognitive symptoms. These patients also tend to develop psychiatric disorders as well, like depression, anxiety, or obsessive-compulsive behavior.
What age do symptoms of Huntington’s disease start?
Huntington’s disease symptoms may start at any age. However, this situation will depend on the CAG repeat length.
If it is too long, the symptoms may start earlier, as much as 2 to 4 years. On the other hand, although unlikely, patients may develop Huntington’s disease symptoms at eighty years old as well.
These patients may have an alteration on the Huntington gene but may not express it at all. The usual range of age for symptoms to start is from the thirties to fifty years old.
Importantly, the disease’s progression may be quicker on patients who develop the disease in the early stages of life.
What are the early stages of Huntington disease?
There are five stages of the progression of HD. Stage 1 and 2 are considered to be the early stages of the disease.
Stage 1, being the early stage, starts at disease onset and can last up to eight years. At this point, the person already has the diagnosis of Huntington Disease but is fully functional at everyday activities.
Driving, work, handling finances, and living performing daily activities such as dressing, bathing, and cooking can be handled with no difficulties. At this stage, the patients typically do not experience motor symptoms.
Nonetheless, they may experience mild cognitive symptoms such as difficulty thinking through complex problems. Additionally, minor psychiatric changes, like irritability and disinhibition, can be present.
Stage 2, being the early intermediate stage, can last between three and 13 years from disease onset. At this stage, the patient is mostly able to carry out daily activities, but may have some difficulties or require little assistance.
The patient may also be unable to do a specific task, needing significant help, while other activities can be done independently. Huntington’s chorea, which is irregular and involuntary movement in many areas of the body, can appear at this stage. Besides, in stage 2, the person with this disorder is still functional at work, but at a lower capacity.
What are Juvenile Huntington’s disease symptoms?
Huntington´s disease symptoms’ characteristics rely on three fundamental pillars of cognitive, motor, and psychiatric. However, in JHD cases, the symptoms may slightly vary from adult-onset HD.
The presentation may depend on the CAG repeat length, including it may develop symptoms earlier and faster. The HD symptoms are the following.
- Involuntary jerking or writhing movements (chorea), it may be mild or non-existent
- Muscle issues, such as rigidity or muscle contracture (dystonia)
- Slow or strange eye movements.
- Abnormal movements, posture, and stability
- Problem with speech or swallowing
- Seizures, especially in children who develop symptoms before age 10
Impairment of voluntary movements, rather than involuntary movements, may impact a patient’s ability to work, perform daily activities, communicate, and remain independent. Nonetheless, these other symptoms may affect children and adolescents as well.
- Muscles become rigid and difficult to move, so they affect the gait (especially in young children)
- They could have sparse involuntary movements that look like tremors
- The patient tends to fall very often or have clumsiness
Among the cognitive symptoms, we can find the following:
- Distress while organizing, prioritizing, or centering on assignments or duties
- Reduction of adaptability or the tendency to get grounded on an attitude, conduct, or activity.
- Loss of impulse control that can result in outbursts, acting without thinking, and sexual promiscuity
- Lack of awareness of one’s behaviors and abilities
- Slowness in processing thoughts or ”finding” words
- Difficulty in learning new information
Importantly, cognitive symptoms may be the first signs and symptoms that children may present with Juvenile Huntington’s disease.
Children and adolescents with juvenile HD frequently have a speedy deterioration in class performance. Their ability to think or reasoning has a significant decrease. These are alarm signs that, along with the other symptoms, may lead to this specific diagnosis.
The most common psychiatric disorder that has a direct correlation with Huntington’s disease is depression. It does not happen just as a reaction after receiving the diagnosis of Huntington’s disease. Surprisingly, it appears to occur after continuous injury to the brain and subsequent changes in brain functionality.
Among the signs and symptoms, we may also find:
- Feelings of anger, frustration, sadness, and fear.
- Social Withdrawal
- Fatigue and loss of energy
- Aggressive behavior
Other common psychiatric disorders asides from depression may include:
- Obsessive-compulsive disorder is a condition marked by recurrent, intrusive thoughts and repetitive behaviors
- Mania which is an exalted mood, overactivity, unpredictable behavior, and exaggerated self-esteem
- Bipolar disorder, an ailment with alternation of events between depression and mania
Asides from enduring all of these symptoms, it is very common that Huntington’s disease patients experience weight loss. This is a symptom that may worry them, adding up to the psychiatric symptoms and being a source of stress for them and their family.
What is the difference between Huntington’s disease and Huntington’s chorea?
There is a significant difference between these two terms. Huntington’s disease is a conglomerate of symptoms that includes not only motor symptoms but also cognitive symptoms.
The name of the disease refers to an affection caused by the mutation in the HTT gene, which causes a series of defective proteins within the brain that will ultimately deposit within the neurons (the cells in the brain). When these proteins deposit themselves within the neurons, it will cause them further death.
Nonetheless, a study reveals that it may also cause alterations in the nerve impulse. Huntington’s disease is the result of the repetition of the trinucleotide CAG on the fourth chromosome.
This is an inherited disease, and it can come from either the father or mother, but the most common is the father. It is a dominant defect, which signifies that anyone who inherits this disease will eventually develop it.
On the other hand, Huntington’s chorea is the hallmark symptom of Huntington’s disease, especially on adult-onset HD. This term refers to a specific physical symptom that causes involuntary body movements.
The characteristics of these movements are short, abrupt, irregular, unpredictable, non-stereotyped movements. These patients often appear fidgety and clumsy.
Overall, chorea can influence multiple body segments, and interfere with speech, swallowing, posture, and cause gait disturbances, but it disappears in sleep.
The source of these movements is because of a functional dysregulation of the basal ganglia motor circuit in the brain. This increases the output of nerve impulses that result in increased movement and chorea.
Can a person with Huntington’s disease have children?
Yes, people with Huntington’s disease can have children. Having this condition does not affect the reproductive system.
Parents will not have trouble having a child unless other conditions may affect reproduction. Nonetheless, these parents should be very aware that there are possibilities for their child inheriting the condition.
It will depend if one or both of the parents are carriers of the disease. In order to know the possibilities, the recommendation is to perform genetic testing on parents to see the extent of gene alteration on them.
The longer the CAG repeat length, there are significant possibilities of their child developing the disease at earlier life stages. There is also the chance of not presenting the disease at all.
Therefore, these children should have genetic testing in the early stages of life to check the cases of inheritance.
Can you detect Huntington’s disease before birth?
Huntington disease is one of the dominantly inherited adult-onset disorders for which prenatal diagnosis is available. There are two specific options for this particular case.
One of them is the direct prenatal diagnosis. During pregnancy, the medical staff analyzes the amniotic liquid through amniocentesis or chorionic villus sampling.
This procedure requires taking a sample of liquid or tissue within your uterus in the pelvis through a delicate method. Then, doctors will analyze its ADN for establishing the presence or absence of the abnormal gene. Also, there is a possibility depending on the situation of termination of pregnancy, if the fetus carries the HD gene.
On the other hand, the preimplantation genetic diagnosis exists in which doctors analyze an embryo obtained by in vitro fertilization. That is to say that couples that want to utilize fertility medical services could have the chance to analyze from several early forms of babies (embryo) obtained the one that does not have the disease gene to be implanted in the woman that will carry out the pregnancy. However, for now, success rates for this procedure are low and are around 20% of success.
What happens if both parents have Huntington’s disease?
Usually, the Huntington gene is passed through the parent’s genes and their children can develop the disease. When having a child, these patients have 50% of the possibilities of inheriting their children’s condition.
This means that these children have 1 out of 2 chances of developing the disease. It is this way because this genetic disorder is a dominant one. Being a dominant disorder means that it has a greater range of possibilities for presenting itself. Having a mutation in only one of the two copies of the HTT gene is enough to cause it.
Now when both of the parents have the gene. It is a different story because, as we said before, this disease is a dominant disorder. Therefore, the possibilities substantially increase.
When both parents decide to have children, they will now have 75% of the chances of inheriting the disease. This is due to the expression of the chromosomes and the Mendel law of gene inheritance.
Hence, it is important to know if you have or not this disease at the time of having a child. These percentages apply for each pregnancy, which means that if you have four children and both parents are positive for Huntington’s disease, there are chances that 4 of them have the disease or 2 of them have the disease.
As you can see, it will depend basically on the gene lottery. Nonetheless, parents may receive genetic counseling if they plan to have a child explore their options.
What is Huntington’s disease treatment?
No treatment can cure or stop the progression of Huntington’s Disease. Nonetheless, some medications can lessen some motor symptoms and psychiatric manifestations.
The medical treatment may vary through the course of the illness, and some medications have side effects that worsen other symptoms. Therefore, the medical follow up is essential for treatment review and update.
The medication used to treat Huntington’s disease patients’ physical symptoms include drugs to control movements. Drugs such as Xenazine and Austedo help suppress the involuntary movements or chorea. Antipsychotic drugs, like Haldol, can also help stop the chorea but can worsen dystonia (involuntary muscle contractions).
The psychiatric symptoms of HD disease can be treated with antidepressants, antipsychotics, and mood-stabilizing drugs. Antidepressants like Prozac and Lexapro are for treating obsessive-compulsive disorder but may cause drowsiness and nausea. Antipsychotics like Seroquel and Risperdal help suppress violent outbursts and agitation but may worsen movement disorders. Mood-stabilizing drugs like Carbatrol and Lamictal help prevent the highs and lows associated with bipolar disorder.
Other treatments for Huntington’s Disease include different types of therapy. Psychotherapy may help the patient develop coping mechanisms and manage expectations during the disease’s progression. HD can affect the muscles of speech, so a speech therapist can help the patient improve his ability to speak clearly.
Finally, a physical therapist may teach exercises that will enhance strength, balance, and coordination.
Does Huntington’s disease skip a generation?
No, it cannot skip generations per se. If it does not occur in one generation, skip to the next, and reoccur in the subsequent generation.
Nonetheless, several cases exist in which Huntington’s disease may appear to skip a generation for one of the following reasons.
- In the past, doctors did not recognize the disease in family members.
- There are times when patients die before developing symptoms. Therefore, they never got the chance to have a diagnosis.
- The scenario in which the parent has the gene but does not express the disease. In light of this, the presence of an intermediate allele or an HTT allele with a reduction in penetrance, which may or may not result in HD in a parent with no symptoms.
- If the disease appears late in life, there is the chance that people live a normal and healthy life till that moment. Hence, it could mean they would have children without knowing they are passing out the disease.
People who do not inherit the HTT gene mutation from an affected parent are not at risk of developing HD. This is because they don’t carry the mutation; they are also not at risk of passing it on to their children. These are the scenarios that may seem like Huntington’s disease skips a generation. Still, it does not mean that it will not be any more running in the family’s blood.
Do you fear that any of your children could have this condition?
This tool is a Juvenile Huntington Disease Symptoms Checker. It gathers the most important signs, symptoms, and risk factors for developing this condition. Therefore, it would help anyone who uses it to determine the likelihood of having Juvenile Huntington’s disease.
If you know there has been this condition in your family, and you are afraid that your children are having symptoms of it, you can use it. Besides, the tool is free and would only take a few minutes to complete.