A very rare genetic condition associated with primary osteoporosis is Osteoporosis Pseudoglioma Syndrome (OPPG), which is caused by a loss-of-function mutation in the low-density lipoprotein receptor-related protein 5 (LRP5) gene, which encodes for Wnt co-receptor LRPR5. Here, LRP5 is linked to osteoporosis-pseudoglioma syndrome.