CLCN7 and autosomal recessive osteopetrosis: CLCN7 loss-of-function mutations lead to autosomal recessive osteopetrosis, characterized by severe skeletal and, often, cognitive phenotype.28 In bone, stunted growth, increased bone mass, and constrain of the bone marrow cavities are observed along with extreme bone fragility, hematological failure, recurrent infections, and osteomyelitis.