Bone mineral status and metabolism in patients with Williams-Beuren syndrome

OBJECTIVE: To evaluate bone mineral status and metabolism in a cohort of patients with Williams-Beuren syndrome (WBS). PA TIENTS: Thirty-one children (15 females, 16 males; mean age 9.6±2.74 years) and 10 young adults (6 females, 4 males; mean age 21.4±5.11 years) with WBS were cross-sectionally evaluated and compared with two age-, sex-, and body-sizematched paediatric (155 subjects, 75 females and 80 males; mean age 9.7±2.93 years) and adult (50 subjects, 30 females and 20 males; mean age 22.3±5.42 years) healthy controls. MEASUREMENTS: We evaluated ionised and total calcium, phosphate, parathyroid hormone (PTH), 25-hydroxyvitamin D, 1, 25-dihydroxyvitamin D, osteocalcin, bone alkaline phosphatase levels, and urinary deoxypyridinoline concentrations. We also calculated the phalangeal amplitudedependent speed of sound (AD-SoS) and the bone transmission time (BTT) z-scores. RESULTS: WBS patients showed a significantly reduced AD-SoS z-score (p <0.001) and BTT z-score (p <0.001) compared with the controls. This finding persisted when we divided the sample into paediatric and adult patients. WBS patients also had significantly higher ionised (p <0.001) and total calcium (p <0.001) levels as well as higher PTH levels (p <0.001) compared with the controls. Furthermore, WBS children and adolescents had significantly lower serum osteocalcin levels (p <0.001) and urinary deoxypyridinoline concentrations (p <0.001) than controls. CONCLUSIONS: WBS subjects exhibit a significant reduction in bone mineral status and impaired bone metabolism. These findings point to the need for close monitoring of WBS patients.