Voltage-gated chloride channel. Plays an important role in membrane repolarization in skeletal muscle cells after muscle contraction. 2 chloride(in) + H(+)(out) = 2 chloride(out) + H(+)(in) Homodimer. Defects in CLCN1 are the cause of autosomal recessive myotonia congenita (MCR). MCR is a disorder of sarcolemmal excitation leading to delayed relaxation of skeletal muscle following contractions. The disease has been identified in the miniature Schnauzer breed. The CLC channel family contains both chloride channels and proton-coupled anion transporters that exchange chloride or another anion for protons. The absence of conserved gating glutamate residues is typical for family members that function as channels (By similarity). Belongs to the chloride channel (TC 2.A.49) family. ClC-1/CLCN1 subfamily.