New Biomarker for Huntington’s Disease Progression Identified

Highlights

• Researchers from Rockefeller University have identified a protein ClC-1 protein that can be used as a marker for disease progression in Huntington’s disease
• Skeletal muscles are found to be affected as the disease progresses leading to loss of motor function.
• Treating skeletal muscle function could improve motor function

Huntington’s disease in mice is found to be associated with defects in muscle maturation, which could be the reason behind the symptoms noticed, according to researchers from Rockefeller University. The study is published in the Journal of General Physiologyand is titled "Progressive Cl− channel defects reveal disrupted skeletal muscle maturation in R6/2 Huntington's mice.” This study found that Huntington’s disease affects the muscle tissue and is a neurodegenerative disorder and that treating the skeletal muscle could aid in improving the condition.

Huntington ’s Disease

This disease condition is a fatal genetic disorder that is characterized by progressive damage to the nerve cells.

• It is caused due to a defective hunting gene which leads to the production of Huntington RNA that is defective.
• The defective Huntington RNA and protein molecules are found to affect the various cellular processes.
• The loss of nerve cells in the striatum and the cerebral cortex is believed to lead to cognitive problems like memory loss and mood swings.
• The defective Huntington gene in the skeletal muscle is believed to be the reason for muscle rigidity and involuntary movements.
• Child with an affected parent has a 50% chance of acquiring this disease
• 30,000 symptomatic Americans
• 200,000 are at risk of inheriting this neurodegenerative disease

Andrew Voss and colleagues from Dayton’s Wright State University, Ohio, and California State Polytechnic University in a previous study examined this disease in mice. They found that there was skeletal muscle damage during the later stages of the disease along with a decrease in function of a protein called ClC-1. This protein is involved in the conduction of chloride ions into the cell. The loss of function of the protein was ascertained to be due to improper RNA or due to the death of neurons in the skeletal muscles. This lead to hyper excitability and other motor function disability.

In the current study, the researchers found that both in the control mice as well as in mice with Huntington’s disease, The RNA that codes for ClC-1 was misprocessed when the mice were young. When the mice grew older, the healthy mice started processing the RNA correctly leading to functional ClC-1. The study highlighted that there was lowered functional ClC-1 in mice with Huntington’s disease which occurred even before the onset of motor disease. This was determined to be due to an absence of muscle maturation in mice with Huntington’s disease.

Andrew Voss surmised his study and said "Our results support the idea that HD is a myopathy as well as a neurodegenerative disease and may provide a new opportunity to improve patient care by targeting skeletal muscle tissue.”

In humans, the symptoms of this disease usually occur between 30 to 50 years of age. As the stage of the disease advances, there is worsening of symptoms over a period of 10 to 15 years. Everyone with the expanded inherited HD gene will develop symptoms for the disease and lose their ability to speak, carry out normal function and lose their memory.

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Symptoms:

The symptoms of the disease include

• Mood swings, memory loss, changes in the personality
• Slurred speech
• Difficulty in swallowing
• Weight loss
• Changes in gait

People with this neurodegenerative condition ultimately succumb to conditions like heart failure or pneumonia.

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In the current study, the loss in function of skeletal muscle cells shows the prospective use as a good target for therapy that will restore at least a part of the function, enabling better control over motor abilities. Apart from this, the study highlights the use of skeletal muscle cells as biomarkers that can be used for staging the disease, instead of brain tissue study.

References:

1. Huntington disease - (https://ghr.nlm.nih.gov/condition/huntington-disease)
2. What Is Huntington’s Disease? - (http://hdsa.org/what-is-hd/)

Source-Medindia