LRP5 and osteoporosis: Interestingly, the genetic loci of proteins involved in the signaling pathways mentioned above, e.g. LRP5, LRP4, Sclerostin, PTH, BMPs or BMP receptor BMPR1B, have already been linked to the polygenetic nature of primary osteoporosis by whole-genome association studies and meta-analyses [27], [28], [29], [30].