CYP27A1 and osteogenesis imperfecta: No significant correlations were found between serum DKK1 level and age, weight, weight Z score, serum levels of P1NP, β-CTX, P, 25-hydroxyvitamin D, sclerostin and OPG or liver and kidney function of children with OI (Fig. 4b, c, f, g, Fig. 5c, d and Supplementary Fig. 1a–b).