We noted no obvious histological signs of neurodegeneration,16 as opposed to the homozygous Clcn7 knock-out21,27,49 and Clcn7G213R homozygous knock-in16 mice that recapitulate the clinical manifestations of autosomal recessive osteopetrosis, but we observed behavioral changes associated with anxiety and depression. This evidence concerns the gene CLCN7 and major depressive disorder.