BGLAP and Osteopenia: This S1PR3−/−-induced osteopenia is a result of a reduced bone formation rate demonstrated by reduced BV/TV (a measure of bone volume) and BFR/BS (a measure of bone formation over time), whilst parameters linked to resorption, e.g., serum osteocalcin(OcN)/bone morphogenic protein (BMP) and collagen degradation products (carboxy-terminal collagen crosslinks: CTX) remained unaffected [29].