Context:The low bone mineral density (BMD) and alterations in bone geometry observed in patients with Turner syndrome (TS) are likely caused by hypergonadotropic hypogonadism and/or by haploinsufficiency of the SHOX gene.
Objective:Our objective was to compare BMD, bone geometry, and strength at the radius between prepubertal girls with TS and children with isolated SHOX deficiency (SHOX-D) to test the hypothesis that the TS radial bone phenotype may be caused by SHOX-D.
Design and Setting:This comparative cross-sectional study was performed between March 2008 and May 2011 in 5 large centers for pediatric endocrinology.Patients: Twenty-two girls with TS (mean age 10.3 years) and 10 children with SHOX-D (mean age 10.3 years) were assessed using peripheral quantitative computed tomography of the forearm.Main outcomes: BMD, bone geometry, and strength at 4% and 65% sites of the radius were evaluated.Results: Trabecular BMD was normal in TS (mean Z-score ϭ Ϫ0.2 Ϯ 1.1, P ϭ .5) as well as SHOX-D patients (mean Z-score ϭ 0.5 Ϯ 1.5, P ϭ .3). At the proximal radius, we observed increased total bone area (Z-scores ϭ 0.9 Ϯ 1.5, P ϭ .013, and 1.5 Ϯ 1.4, P ϭ .001, for TS and SHOX-D patients, respectively) and thin cortex (Z-scores ϭ Ϫ0.7 Ϯ 1.2, P ϭ 0.013, and Ϫ2.0 Ϯ 1.2, P Ͻ .001, respectively) in both groups. Bone strength index was normal in TS as well as SHOX-D patients (Z-scores ϭ 0.3 Ϯ 1.0, P ϭ .2, and 0.1 Ϯ 1.3, P ϭ .8, respectively).
Conclusions:The similar bone geometry changes of the radius in TS and SHOX-D patients support the hypothesis that loss of 1 copy of SHOX is responsible for the radial bone phenotype associated with TS. (J Clin Endocrinol Metab 98: E1241-E1247, 2013)