Key takeaways
- Huntington’s disease is a hereditary neurodegenerative disorder that causes progressively uncontrolled movements, muscle rigidity, emotional problems, and loss of thinking ability, typically appearing in a person’s 30s or 40s.
- Research suggests Huntington’s disease may also affect skeletal muscle tissue, disrupting chlorine and calcium signaling that regulate muscle excitability and contraction. This may explain some physical movement symptoms, such as involuntary movements and muscle rigidity.
- Identifying muscle-related changes in Huntington’s disease may offer biomarkers to help track disease progress without examining brain tissue and may provide new treatment targets for motor function problems.
Huntington’s disease is a hereditary, progressive disorder. It is a neurodegenerative disease, meaning nerve cells in the brain and nervous system progressively lose function and eventually die.
People with Huntington’s disease experience progressively uncontrolled and uncoordinated movements, muscle rigidity, emotional problems, and loss of cognition or ability to think. The most common form usually appears in a person’s 30s or 40s.
The disorder arises from a gene variation that disrupts the DNA translation and subsequent production of the huntingtin protein, which in turn causes brain cell malfunction and death.
Scientists believe the thinking, mood, and behavioral features of Huntington’s disease arise from death of nerve cells in the striatum and cerebral cortex regions of the brain.
However, there is speculation that some of the features that affect motor function – such as involuntary movements and muscle rigidity – could be a result of huntingtin protein alteration in skeletal muscle.
For example, multiple studies in mice models of Huntington’s disease note that the condition affects skeletal muscle.
Some research in human and animal models of Huntington’s disease highlight the role of a chlorine channel protein known as CIC-1. As the name suggests, this protein ferries chloride ions into cells. This helps to regulate the excitability of skeletal muscle.
The term excitability of muscle refers to the ability of muscle cells to generate electrical impulses. This excitability is crucial for muscle contraction and overall function.
Alternations in the CIC-1 proteins can result in hyperexcitability of the muscles and offers a possible explanation for some of the physical movement symptoms of the disease.
Similarly, the huntingtin protein may also influence calcium signaling in muscles, which can also contribute towards hyperexcitability. Calcium also plays a critical role in muscle contraction, as calcium binds to proteins that regulate muscle contraction, which leads to muscle shortening and force generation.
As such, a person living with Huntington’s disease may experience problems with how intensely their muscles can contract. This suggests that Huntington’s disease is also a myopathy, or disease of muscle, as well as a neurodegenerative condition.
Identifying these problems with muscle maturation in Huntington’s disease may offer biomarkers to help track progress of the disease without having to examine brain tissue. It may also provide targets to help address and treat the muscle problems that relate to Huntington’s disease. However, more research, particularly in humans, is still necessary.
While more research is still necessary, some evidence suggests that Huntington’s disease may affect skeletal muscle, as well as brain tissue. This may explain some of the physical movement symptoms of the disease, such as involuntary movements and loss of motor skills.