In the case of ClC proteins, impaired function of ClC-1, ClC-2, ClC-K, ClC-5, and ClC-7 may result in myotonia congenita, azoospermia/leukodystrophy, Bartter syndromes types 3 and 4, Dent’s disease, and osteopetrosis/retinal degeneration/lysosomal storage disease, respectively. The gene discussed is CLCN1; the disease is Thomsen and Becker disease.