Sgpl1–/– mice exhibit an extensive range of other phenotypes, including skeletal (osteopetrosis and dysfunctional osteoclasts), pulmonary (proteinaceous exudates in alveoli impairing gas exchange), cardiac (increased interstitial cellularity and myocardium vacuolation), urinary tract (urothelial cells affected by widespread ballooning vacuolation, degeneration, and apoptosis), thymic (atrophy), and hepatic abnormalities (disruption of liver homeostasis with defective hepatic lipid metabolism) (22, 30, 39). Here, SGPL1 is linked to osteopetrosis.