MC caused by CLCN1 mutations that encode the voltage-gated chloride channel (ClC-1) in the skeletal muscle is classified into the autosomal dominant (AD) Thomsen's myotonia congenita (DMC) and the autosomal recessive (AR) Becker's myotonia congenita (RMC) according to the mode of inheritance. This evidence concerns the gene CLCN1 and Alzheimer disease.