Mutations in at least nine genes cause the various types of osteopetrosis. Mutations in the "CLCN7" gene are responsible for about 75 percent of cases of autosomal dominant osteopetrosis, 10 to 15 percent of cases of autosomal recessive osteopetrosis, and all known cases of intermediate autosomal osteopetrosis. "TCIRG1" gene mutations cause about 50 percent of cases of autosomal recessive osteopetrosis. Mutations in other genes are less common causes of autosomal dominant and autosomal recessive forms of the disorder. The X-linked type of osteopetrosis, OL-EDA-ID, results from mutations in the "IKBKG" gene. In about 30 percent of all cases of osteopetrosis, the cause of the condition is unknown.