Prader-Willi syndrome is a complex
genetic disorder with a characteristic cognitive, behavioral, and endocrinologic phenotype.
Obesity, partial
growth hormone (GH) secretion, and
hypogonadism are common. Results of several
somatropin (GH
therapy) studies in children with
Prader-Willi syndrome have shown improvement in growth, body composition, physical strength, and agility. GH deficiency in adults without
Prader-Willi syndrome is associated with
abdominal obesity,
insulin resistance, and an unfavorable
lipid profile, and the partial state of GH deficiency seen in
Prader-Willi syndrome thus renders these patients exposed to a lifelong risk of
metabolic diseases. The nongrowth effects of
somatropin in children with
Prader-Willi syndrome have directed interest towards adults in preventing long-term consequences of GH deficiency, but the potential impact of
somatropin therapy in adults with
Prader-Willi syndrome is not known in detail. To date, only one study has been published. In this study, 17 patients (9 men and 8 women) with a mean age of 25 years and a mean body mass index of 35 +/- 3.2 kg/m2 were examined. Eleven had the
Prader-Willi syndrome genotype. They were treated with
somatropin (
Genotropin) for 12 months after an initial placebo-controlled period of 6 months. Compared with placebo,
somatropin increased
insulin-like growth factor-1 levels (p < 0.01) and decreased body fat (p = 0.04). During the 12-month period with
somatropin therapy, the mean reduction in body fat was 2.5% (p < 0.01), concomitant with a mean increase in lean body mass of 2.2kg (p < 0.05).
Lipid profiles were normal in most patients before treatment and did not change. The oral
glucose tolerance test was impaired in one patient at study start and in five patients at 12 months. No patients developed
diabetes mellitus. Furthermore,
insulin levels remained unchanged, and estimation of
insulin resistance by homeostasis model assessment did not disclose any change. Transient adverse effects attributed to water retention occurred in three patients. In conclusion, the one published study of
somatropin therapy in adults with
Prader-Willi syndrome showed beneficial effects on body composition without pronounced adverse effects. However, further studies are required to establish the definite role and optimal dosage of
somatropin, as well as long-term effects, in adults with
Prader-Willi syndrome.