This group encompasses various diseases, including sclerosteosis-1, Juvenile Paget’s disease (JPD)-5, Ghosal hematodiaphyseal dysplasia (GHDD), primary hypertrophic osteoarthropathy (PHOAR) types 1 and 2, caused by biallelic mutations in SOST/LRP4, TNFRSF11B, TBXAS1, and HPGD/SLCO2A1, as well as craniometaphyseal dysplasia (CMD) and Camurati-Engelmann disease (CED), caused by monoallelic mutations of ANKH and TGFB1, respectively [1–3]. Here, SLCO2A1 is linked to juvenile Paget disease.