The G215R allele of CLCN7, used here to reduce CLCN7 function in the mouse, was originally identified in a patient with dominant osteopetrosis [50] which results from impaired osteoclast-mediated bone resorption and is thus physiologically quite different from the deposition defect in FIG4 mutants. This evidence concerns the gene CLCN7 and osteopetrosis.