Huntington’s Disease – causes, symptoms, diagnosis, treatment

Huntington’s Disease is a brain disorder. This disorder is also termed Huntington’s chorea on chromosome number 4 a single abnormal mutant gene is responsible for a gradual brain disorder. Huntingtin’s protein is the blueprint of infected gene codes. This disease results in the death of brain cells. It is an autosomal dominant disorder. This Huntingtin’s protein is also a cause of this disease. This disease was firstly described by “George Huntington’s”.

The form of this disease that appears in older persons is known as adult-onset Huntington disease. It is the most commonly known form of this disease which mostly develops at the age of thirty or forty. This causes a jerking movement which is known as chorea. This causes trouble in learning new information and making decisions.

Another form that is least common is known as a juvenile form which may occur from childhood. It may affect the emotions of a child and one’s movements. It also affects the abilities like reasoning and thinking. Its effects increase more rapidly than the last form of this disease.

All the individuals have two copies of Huntingtin gene, which produce Huntingtin protein. The other term used for this gene is HD and IT15 which is abbreviated as interesting transcript 15 and has a part known as trinucleotide repeat that has a variable length in individuals or in generations.

If mutations occur that may increase the repetition and defect the gene. A defective gene produces another protein which is called mutant Huntingtin protein. The main cause of this disease is the different functions of these proteins. This disease is not inherited according to sex and its severity is influenced by the length of the repeated sections.

It has autosomal dominant inheritance. It means that each person has one copy of a gene which is inherited from the affected parent. There are 50% chances to inherit mutant allele from affected parents of offspring. And this type of inheritance in sex-independent. There are some rare cases in which both parents have mutant genes which expand the risk to 75%.

In inheritance, it can be caused due to the carrier which is the father or mother but in some cases it can be caused due to the mutation in the prospective gene. This can be passed from one generation to the next, as this progresses from generation to next there is an increase in the repetition of the huntingtin gene.

Stages of disease

Early-stage

At the early stages of disease patients are not affected by failed motor symptoms but may experience mild cognitive and psychiatric symptoms. And this stage may last for 8 years.

Early intermediate stage

At this the functional abilities reduce of the affected person. At this stage involuntary movements start at different parts of the body and the affected person may need some assistance while doing some heavy work or functions. This stage can last for 3 to 13 years.

Late intermediate stage  

This stage may last for 5 to 16 years. At this the person depends on others to perform his daily routine.  His/her thinking ability gets more impaired, anxiety and impulsiveness become evident.

Early advanced stage

 This stage may last for nine to 21 years. At this stage patients need assistance to perform domestic activities. The patient may be aware of what to do and what not to do but he/she may require help to act.

Advanced stage

At this stage the affected person needs total support and help to perform activities. At advanced stages the symptoms get worse such as teeth grinding and abnormal limb posture. At this stage the patient faces problems in temperature and blood pressure and his ability to swallow gets worsen.

Frequency

This disease affects approximately 3 to 7 persons out of 100,000 people in the countries of Europe. This disease also affects the people of other countries such as Japan, China and Africa but rate of this disease in these countries is much lesser than European countries. This disease affects both male and female equally.

Causes

It is inherited as an autosomal dominant disorder. Only one copy of mutant gene is required or needed to develop this disease. Two copies of genes are present in each individual of every gene, each copy from both father and mother. So, in this way the copy of this defected gene may pass from one parent to the child along with an unaffected copy.

So, every newborn in the family has a 45-50% chance to develop this disease. The mutant gene on chromosome number 4 is responsible for Huntington’s disease and was discovered in 1993. The HHT gene provides information for production of a gene called Huntington. This gene has unknown functions to perform but it has important functions in the brain and in brain cells.

The Reason for this disease is the repetition of the DNA segment which is known as CAG trinucleotide. In normal conditions the repetition of this segment is 10 to 35 in a gene but the person who is infected by this mutation or disease this repetition may increase from 36 to more than 120 times.

If the CAG segment repeats 36 t0 39 times may or may not develop the signs of this disease, but the person who has replenishment of this segment increases from 40 or above almost develops this disease. Due to this disorder the manufactured Huntingtin protein cut into small toxic fragments and accumulated in the brain or neurons and disturb the normal functions of cells.

Symptoms

The symptoms of this disorder vary from person to person. Symptoms of this disorder are unconscious head movement, face, legs, arms and upper parts of the body. Changes in brain cause mood changes, anxiety, long-term tension, irritability and anger. Affected person shows abnormal eye movement.

It also affects the phenomena of swallowing of affected person.  The person becomes habitual for repeating same question or activity over and over. This disease also affects the cognition of diseased person. Other symptoms such as insomnia, fatigue and loss of energy. The effected person may frequently think about dying and suicide. It also affects one’s behavior.

Symptoms usually appear at the ages of 32 and 51. At early age it can appear at age of 2 or may be late at age of 80. Peoples suffering from this disorder have chances to survive with an average of 15 to 20.

Metabolic symptoms

This disease may cause metabolic disturbance. Which may include catabolic loss of weight, disturbance in the endocrine system and the affected person may face sleepiness.

Motor symptoms

These symptoms are divided into two classes. Involuntary movements and impaired voluntary movements. This causes the involuntary hand movements and may cause incoordination in limbs. The patterns of these symptoms may change and could be worse by time.

Psychiatric symptoms

The most common symptom is depression. In a recent report that shows that the people having this disease 40% had depression. Other symptoms of this category include psychosis.

Other symptoms of this disease may include dysphasia and dysphagia which is the combination of effects in motor neurons and language difficulties.

Other psychiatric symptoms include:

Obsessive-compulsive disorder It includes repetitive behaviors and interrupting thoughts.

Mania It may cause overactivity, impulsive behavior and self-esteem.

Some other symptoms in addition to the above-mentioned symptoms which are linked with this disease may be weight loss as disease progresses.

Advanced stage of disease

As time pass the patient become disable. One’s communication ability becomes limited and muteness is common. At advance stages the patient becomes frustrated and due to catabolic problems and insufficient diet the affected person cannot maintain his weight.

Progression of disorder

This disease can progress and its severity can increase by time. The effects of this condition is different in different persons and its symptoms are also different which depends upon the progression of disease. The symptoms of this condition are well defined but their rate of progression and phenomena of progression is still unexplainable.

Time period of this disease is variable. It may cause death of affected person after 19 years as the symptoms were developed. As the disease progress it may cause some serious problems related to heart and which ultimately results in death.

The repetition of affected genes is the indicator of the different stages of this condition. Genetic factors as well as some physical influences or factors or environmental factors have a role in the progression of this condition. This influence of these factors also talks about the different types of this condition.

Causes

It is inherited as an autosomal dominant disorder. Only one copy of mutant gene is required or needed to develop this disease. Two copies of genes are present in each individual of every gene, each copy from both father and mother. So, in this way the copy of this defected gene may pass from one parent to the child along with an unaffected copy.

So, every newborn in the family has a 45-50% chance to develop this disease. The mutant gene on chromosome number 4 is responsible for Huntington’s disease and was discovered in 1993. The HHT gene provides information for production of a gene called Huntington. This gene has unknown functions to perform but it has important functions in the brain and in brain cells.

The Reason for this disease is the repetition of the DNA segment which is known as CAG trinucleotide. In normal conditions the repetition of this segment is 10 to 35 in a gene but the person who is infected by this mutation or disease this repetition may increase from 36 to more than 120 times.

If the CAG segment repeats 36 t0 39 times may or may not develop the signs of this disease, but the person who has replenishment of this segment increases from 40 or above almost develops this disease. Due to this disorder the manufactured Huntingtin protein cut into small toxic fragments and accumulated in the brain or neurons and disturb the normal functions of cells.

Complications

As this disease starts the functional and mental abilities of the affected person becomes worse as time passes. The duration and rate of progression of this disease varies. This may increase the risk of disease in the middle stages of disorder because a person starts to lose independence.

The affected person needs care and help in daily activities but in the last stages of disorder the person may lay on bed and be unable to speak. In juvenile form the death may occur after 10 years as symptoms develop. It may also increase the chances of suicide in affected person and the death rate by suicide is 9% in this case.

Diagnosis

Commonly some problems are related with Huntington’s disease-carrying persons different but several tests are performed for diagnosis of this disease. Some are genetic testing, pre-implantation, genetic, but the council of genetics gives information about the guidance leading in the procedure of the test. Some abnormalities due to Huntington’s disease are

  • lessen of weight,
  • Heart attack
  • Atrophy of muscle and testes
  • Mode becomes off
  • No coordination
  • Mentally disorder
  • Particular symptoms vary from person to person
  • Symptoms can appear at any age but mostly between 30-50 years.
  • Steady movement is difficult.

Mostly Huntington’s disease is inherited by their parents but in a few cases new mutations occur. If the human being has a mutation that is dominant not sexually but autosomal in two copies of genes, the child of that person will have a half chance of disease spreading.

Diagnosis is also done by brain imaging.  It may include MRI or CT scans which provide detailed images of brain functioning. These tests observe the changes in brain structure and functions and also talk about the other conditions which may cause symptoms.

Management

The aim of management is to improve quality of life. There are many options to manage the symptoms which can be by drug and non-drug method. The non-drug-based management is more effective than drugs. This can be managed by teams of professionals which may include neurologists, psychiatrists and physiotherapists etc.

It is an incurable disease. But some medicines are available to reduce the severity of the disease. Genetic testing is used to reduce the chances of this disease. Other diseases concerned by this are Huntington’s disease-like syndromes. Mutations are common cause in Huntington’s disease like diseases some types are Huntington’s like 1, 2, 3 & 4.

Therapy

Muscle malfunction are dietary problems commonly associated with this condition. So nutritional management should be proper as disease develops to its further stages. Liquid food should be in thick form and the affected person should eat the food slowly. In case of physical problems, a patient should see a physiotherapist who will conduct some exercise related to cardiovascular, walking and breathing exercise.

Treatment

The treatment involves management of symptoms. No treatment for this disorder yet. It is treated by some medicines to slow down its effects. The current treatment is given to lower the symptoms of disorder such as abnormal movements and behaviors. Suicide is more common in effected people and they should be monitored for care and assistance.

The changes that are caused by this gene in the brain cannot be slow or stop managing symptoms is somewhat treatment. Medication can control improper movements. To control speaking problems speech therapy is useful. Some devices can be used to control movement problems. Exercise is another option to control movement problems.

The affected people need more care and help from their families as their condition get worse as the disease progresses to the later stages. They should be helped in their daily life activities and to perform their professional works.

Prevention 

The people belong to families which have histories about Huntington’s disorder. These persons should consult a genetic counselor and family planning. Genetic counselors will talk about the risk of positive results that will indicate the chances of disease to be developed in the next generation.

Another method to prevent this disorder is to remove the eggs from mother’s ovaries and then fuse it with the sperm of father in the laboratory and then after fertilization the embryos are diagnosed to check the occurrence of this disorder. If the result is negative then the embryo is implanted in the mother’s uterus.

Precaution

Daily routine changes are also helpful in controlling air passage diseases. By this change the functional loss becomes less. Involvement of routine changes during the control step of life is responsible for CNS proper working. The persons who are suffering from Huntington’s disease should eat a proper balanced diet.

The most watery but thicker things should be used because it is easy to pass in through track. Infected Huntington’s disease people have to eat regularly but slowly and small bytes of meal to or remain protective from this disease. When the disease is great and affects the person because less caused by himself. Overuse of caffeine in tea is also a cause of this disease. Sexually chromosomal linked diseases are also seen.

 

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