The CLCN family of voltage-dependent chloride channel genes comprises nine members (CLCN1-7, Ka and Kb) which demonstrate quite diverse functional characteristics while sharing significant
sequence homology. The protein encoded by this gene regulates the electric excitability of the skeletal muscle membrane. Mutations in this gene cause two forms of inherited human muscle disorders: recessive generalized myotonia congenita (Becker) and dominant myotonia (Thomsen).
Chloride channel protein, skeletal muscle (CLCN1) is a
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...
that in humans is encoded by the ''CLCN1''
gene
In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...
.
Mutations in this protein cause
congenital myotonia.
CLCN1 is critical for the normal function of skeletal muscle cells. For the body to move normally, skeletal muscles must tense (contract) and relax in a coordinated way. Muscle contraction and relaxation are controlled by the flow of
ions
An ion () is an atom or molecule with a net electrical charge.
The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conven ...
into and out of muscle cells. CLCN1 forms an
ion channel that controls the flow of negatively charged chloride ions into these cells. The main function of this channel is to stabilize the cells' electrical charge, enabling muscles to contract normally.
In people with congenital myotonia due to a mutation in CLCN1, the ion channel admits too few chloride ions into the cell. This shortage of chloride ions causes prolonged muscle contractions, which are the hallmark of myotonia.
See also
*
Chloride channel
Chloride channels are a superfamily of poorly understood ion channels specific for chloride. These channels may conduct many different ions, but are named for chloride because its concentration ''in vivo'' is much higher than other anions. Several ...
*
Thomsen disease
References
Further reading
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
External links
GeneReviews/NCBI/NIH/UW entry on Myotonia Congenita*
*
Chloride channels
{{gene-7-stub