Effect of genetic subtypes and growth hormone treatment on bone mineral density in Prader-Willi syndrome

Background: Currently, there is limited information on the effects of growth hormone and of the different genetic subtypes on bone mineral density (BMD) in Prader-Willi syndrome (PWS). Methods: We evaluated BMD in 79 individuals with the common subtypes of PWS (48 with deletion and 27 with UPD) and the effect of growth hormone treatment (n=46) vs. no growth hormone treatment. Results: Forty-four percent of the individuals studied had whole body, hip, or spine BMD <-1 standard deviation (SD) and 10% had a BMD <-2 SD. BMD Z-scores and total BMD (g/cm(2)) of the spine were significantly higher in the growth hormone group. With each year of growth hormone treatment, these values increased by a factor of 0.207 and 0.011 (p=0.006 and 0.032), respectively. Individuals with uniparental disomy revealed higher spine BMD compared with deletion subclass; however, the differences were not significant. Conclusion: This study emphasizes the importance of evaluating bone mineralization in individuals with PWS and the beneficial effects of prolonged treatment with growth hormone. There was a trend for a higher BMD in individuals with uniparental disomy.