All previous information has been reviewed and is up to date.

The following article summary is a continuation of the article “ Growth hormone improves mobility and body composition in infants and toddlers with Prader-Willi syndrome” summarized above.

Myers, S. E., Whitman, B. Y., Carrel, A. L., Moerchen, V., Bekx, M. T. and Allen, D. B. (2007), Two years of growth hormone therapy in young children with Prader–Willi syndrome: Physical and neurodevelopmental benefits. Am. J. Med. Genet., 143A: 443–448. doi:10.1002/ajmg.a.31468

The purpose of the study was to determine the effects of early intervention growth hormone (GH) therapy on body composition, anthropometric measurements, and psychomotor development in infants and toddlers with Prader-Willi syndrome (PWS). The study involved the enrollment of twenty-five infants and toddlers, ages 4-37 months, with PWS. The subjects were randomized into two groups: two years of GH therapy (1 mg/m2/day) or one year of observation without treatment, followed by one year of GH treatment (1.5 mg/m2/day). Dual-energy x-ray absorptiometry (DEXA) was utilized to determine percent body fat, lean body mass, and bone mineral density, while x-rays of the left hand determined bone age. All measurements were repeated at 12-month intervals. Throughout the study, all patients received home-based physical therapy and speech therapy through the early childhood intervention program.

Motor development was determined by Toddler and Infant Motor Evaluation (TIME) and age of independent walking, while cognitive and language skills was assessed by the Capute Scales of Infant Language Development. Physical therapists, who were blinded to the study, assessed mobility and stability bi-annually using the TIME. The raw scores, centiles, and length/height standard deviation scores were analyzed to determine developmental growth in each group. Data was analyzed via the Statistical Analysis System using a t-test comparison between treatment and non-treatment groups linked to baseline, year 1, and year 2. Subjects who received GH experienced normalized height, increased lean body mass, and decreased percent body fat (P<0.005 for all parameters), along with increased development in language (P=0.05) and cognitive (P=0.02) abilities after 1 year of treatment compared to the non-treatment group. The 2 year data showed that accumulation of excess body fat was reduced and delayed, however, it was not prevented completely, and that independent walking age was reported to be 23.3 ± 4.8 months, slightly less than previously studied. Overall, GH was tolerated well, except for one reported case of scoliosis, and those treated were said to be more alert and energetic by their parents.

Major strengths of the study include that it was a blind, randomized controlled trial, performed over 2 years, and resulted in positive outcomes. The limitations of the study include decreased amount of change detectable in mobility and stability due to the floor effects of the TIME, there was no information regarding cooperation of therapy or the treatment provided, limited number of subjects, and that the results of the control group after the second year was not given. In conclusion, the study prompts that early referral to pediatric endocrinologist for consideration of GH therapy is beneficial in infants and toddlers with PWS.