In contrast, in this study, we have used peripheral blood gene expression profiling as the source for gene expression profiles, and show that these patterns can be used to predict response to r-hGH in each year of treatment up to 5 years in two different growth disorders that account for ~60% of GH prescriptions in the USA, Europe and the UK [19, 20]. The gene discussed is GH1; the disease is hereditary endocrine growth disease.