Growth hormone therapy in young children with Down syndrome and a clinicalcomparison of Down and Prader-Willi syndromes

The genetic disorders Prader-Willi syndrome and Down syndrome have a number of features in common, for example, both growth and mental retardation. Gr owth hormone (GH) treatment is becoming part of the clinical management of children with Prader-Willi syndrome, but in children with Down syndrome, su ch therapy is still on a research level. In this review, we compare the cli nical phenotypes of the two syndromes, and report the effects of long-term GH treatment on the linear growth and psychomotor development of 15 young c hildren with Down syndrome (mean age at start of treatment, 7.4 months). Th e mean height of the treated children with Down syndrome increased signific antly from -1.8 to -0.8 SDS (Swedish standard) during the 3 years of GH the rapy (P < 0.001). The mean height of a corresponding control group fell fro m -1.7 to -2.2 SDS. After the cessation of treatment, growth velocity decli ned in the treated group. Growth of the head did not increase during GH tre atment. There was no effect on mental or gross-motor development, although some improvement in fine-motor development was noted in the GH-treated grou p (P < 0.01). At present, treatment with GH is not recommended in children with Down syndrome who have not been diagnosed with GH deficiency. Long-ter m studies with an emphasis also on the metabolic effects of GH therapy are necessary before routine treatment can be considered in such children. (C) 2000 Harcourt Publishers Ltd.