Most of them cause known monogenic disorders, such as osteogenesis imperfecta (COL1A1/COL1A2), pycnodysostosis (CTSK), X-linked osteoporosis (PLS3), osteopetrosis, X-linked hypophosphatemia (PHEX), and osteoporosis pseudoglioma syndrome (LRP5) [43]. This evidence concerns the gene LRP5 and X-linked hypophosphatemia.