For example, the Osteoporosis-Pseudoglioma Syndrome (OMIM 259770) is caused by loss-of-function mutation of the low-density lipoprotein receptor-related protein 5 (LRP5), which is a co-receptor involved in WNT signal transduction [97], while gain-of-function mutations of the same gene result in hyperostosis (OMIM 144750) [98]. Here, LRP5 is linked to hyperostosis.