–OPG levels in normal children (aged 1–14 years) were highest in infancy and decreased with increasing age.–No correlation between OPG levels and BMI, height, weight, puberty.–OPG levels in TS cohort were lower than normal in age and sex-matched controls.–No difference in RANKL levels between TS and controls. Here, TNFRSF11B is linked to Timothy syndrome.