In our study, we observed higher concentrations of periostin in children with PWS than in the healthy controls and significant positive relations with osteocalcin and Gla-OC, which may be the result of increased protein carboxylation processes dependent on vitamin K. Additionally, periostin stimulates the Wnt signaling pathway, inhibiting the expression of sclerostin to mediate the anabolic response of the bone [7]. This evidence concerns the gene SOST and Prader-Willi syndrome.