CLCN7 and lysosomal storage disease: ADO2 is not considered a disease affecting the brain, as opposed to CLCN7-depended autosomal recessive osteopetrosis in which severe neurodegeneration and lysosomal storage disease can be observed in patients.1,11,48 However, a few ADO2 patients were reported to present with cognitive failures.4,14 Systematic studies on brain involvement in ADO2 patients are not available and manifestations like anxiety and depression, if noted, may be underestimated as they could be nonspecifically associated with any illness status.