CLCN1

CLCN1 is a gene that provides instructions for making a protein that is critical for normal muscle function. This protein, called the chloride channel protein 1, is found in skeletal muscle cells, which are the cells that make up muscles used for movement. The chloride channel protein 1 is involved in generating and transmitting electrical signals that lead to muscle contraction.

Function

The chloride channel protein 1, produced by the CLCN1 gene, forms a channel that controls the flow of chloride ions into skeletal muscle cells. This flow of ions is essential for maintaining the electrical stability of these cells. The stability helps regulate muscle cell excitability, which is the ability of the cells to respond to stimuli and contract.

Genetic Changes

Mutations in the CLCN1 gene cause a disorder known as myotonia congenita. This condition is characterized by the inability of the muscles to quickly relax after voluntary movements. The most common mutation that causes myotonia congenita replaces the amino acid cysteine with the amino acid tyrosine at position 277 in the chloride channel protein 1 (written as Cys277Tyr or C277Y). This mutation disrupts the normal function of the chloride channel, reducing the flow of chloride ions into muscle cells. As a result, the cells become hyperexcitable, leading to prolonged muscle contractions.

Associated Disorders

Myotonia Congenita: This is a genetic disorder that affects skeletal muscles. People with this condition have muscle stiffness (myotonia) and cannot relax certain muscles after use. There are two forms of myotonia congenita, Becker type and Thomsen disease. Both are caused by mutations in the CLCN1 gene.

See Also

• Chloride Channels
• Myotonia Congenita
• Becker Type Myotonia Congenita
• Thomsen Disease

References

• Genetics Home Reference. (n.d.). CLCN1 gene. Retrieved from https://ghr.nlm.nih.gov/gene/CLCN1
• OMIM. (n.d.). CLCN1 chloride channel, voltage-sensitive 1; CLCN1. Retrieved from https://www.omim.org/entry/118425

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