Medical illustration of the symptoms of Huntington's disease in the brain
Medical illustration of the symptoms of Huntington's disease in the brain

There diseases are numerous. Alzheimer’s disease is perhaps the most talked about these days, but there are many others, all of which can have a profoundly negative impact on a person’s health and quality of life. One of those is Huntington’s disease, or HD for short, which affects 30,000 people in the US currently, with another 200,000 people at risk of developing the disease.

What Is Huntington’s Disease?

According to the Huntington’s Disease Society of America, HD is defined as,

“a fatal genetic disorder that causes the progressive breakdown of nerve cells in the brain. It deteriorates a person’s physical and mental abilities during their prime working years, and has no cure. HD is known as the quintessential family disease because every child of a parent with HD has a 50/50 chance of carrying the faulty gene.”

The Mayo Clinic expands on this definition.

“Huntington’s disease has a broad impact on a person’s functional abilities and usually results in movement, thinking (cognitive) and psychiatric disorders. Most people with Huntington’s disease develop signs and symptoms in their 30s or 40s, but the disease may emerge earlier or later in life.”

The most common type is adult onset, which may occur at any point in an adult’s life, but is most common in the 30s and 40s, as mentioned. Juvenile Huntington’s disease, on the other hand, is far rarer and begins during childhood or a patient’s teen years.

In both types, a person’s lifespan is dramatically reduced. For adults with HD, it is usual to live 15 to 20 years after the first signs are noticed. Children with this disease may only live 10 to 15 years after the first signs.

What Are the Signs and Symptoms of Huntington’s Disease?

Because HD can affect an individual’s physical and mental state, it is possible to notice an incredibly wide range of symptoms, even during the early stages of development. Note that the signs and symptoms also vary between adults and children. Some of the most common symptoms and signs of HD include the following (for adults):

  • Slurred speech
  • Difficultly controlling muscles
  • Impaired gait
  • Involuntary movements or writhing
  • Slow eye movements
  • Difficulty with speech
  • Difficulty swallowing
  • Difficulty focusing on tasks
  • Mental rigidity
  • Lack of impulse control
  • Lack of awareness of one’s own behaviors
  • Difficulty learning new ideas or concepts

For children, the signs and symptoms can include:

  • Rapid emotional changes
  • Difficulty with physical movement
  • Clumsiness
  • Slurred speech
  • Frequent falling
  • Loss of learning
  • Seizures

One of the greatest risks of Huntington’s disease is patients’ propensity to suicide. Frequency of suicide in Huntington’s patients is 8-10 that of the general population.

What Causes Huntington’s Disease?

While science might not understand how the changes happen, mutation within the patient’s HTT gene is the cause of Huntington’s disease. This gene is responsible for the creation of a protein called huntingtin, which plays a role in the production of neurons (brain cells). The mutation in question involves the CAG trinucleotide repeat.

In a normal gene, this segment may repeat up to 35 times. However, in those with HD, it may repeat between 36 and 120 times. If the number of repeats is low (under 40), the individual may only be a carrier, and symptoms may never manifest. Those with 40 or more repeats will develop the disease at some point, with a higher number of repeats coinciding with an earlier onset.

Because of the greater number of repeats, the gene creates a version of the huntingtin protein that is too long. The body cuts these proteins up into shorter segments, which are toxic. They then bind together with brain neurons creating dysfunction and eventual death of the cells.

What Are the Treatment Options?

There is currently no cure for Huntington’s disease. There are only management methods. Currently, medications can help to manage some of the symptoms of the disease. However, these medications are not without side effects, some of which can actually cause other symptoms to worsen.

How Can Stem Cell Therapy Help?

Stem cells are the progenitors to all other cell types in the body. They are also the key healers, and can transform into any other type of cell necessary. The problem is that the efficacy and number of stem cells in the human body decreases as we age. Research using stem cell implantation for treating Huntington’s disease and other diseases is ongoing, and all surround the concept of stem cells healing and/or replacing dead or dying neurons. In a study published in the International Journal of Stem Cells, the authors note,

"Stem cells can play an important role in cell therapy therapeutic strategies to replace dysfunctional or dying cells in HD."

The study discussed numerous types of stem cells, including mesenchymal stem cells derived from bone marrow, those derived from fat tissue, and induced pluripotent stem cells (iPS, or forced immature cells). Writing about stem cell types, the study’s authors note,

"Overall, stem cells have much potential for use as a source of cell therapy for HD, however stem cells used for autologous transplantation, such as MSCs, ASCs and iPS cells, themselves also carry the mHtt gene. Thus, more study is needed to ensure the survival and functional effects of stem cells derived from HD patients."

The Use of Allogeneic Stem Cells

Rather than using autologous stem cells and encountering the numerous issues cited by the study’s authors, an alternative is available. Allogeneic stem cells are sourced from umbilical cord blood and tissue, providing access to natural pluripotent stem cells exactly like embryonic stem cells (ESCs), but without the ethical issues surrounding those cells. Allogeneic stem cells lack the mHtt mutation present in a patient’s own cells, and are immune-naïve, so there is no chance of inciting a negative immune system response.

Ultimately, stem cell therapy shows enormous promise for those suffering with Huntington’s disease and their children. However, there is as yet no FDA-approved stem cell treatment for humans. All such treatments are experimental only.

Source:

Huntington's Disease Fact Sheet
Huntington’s disease: how could stem cells help?
Stem Cells Strike Back Against Huntington’s Disease
Stem Cells Transplantation and Huntington’s Disease
Paramedic Stem Cells Show Potential as a Treatment for Huntington’s Disease in Mouse Studies
What Is Huntington’s Disease?
Huntington's disease

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