IGF1 and Laron syndrome: However, patients from the Backeljauw et al study were all naïve to IGF-1 therapy; started treatment at a younger age; had a lower HtSDS and height velocity at baseline, suggesting a more severe phenotype; and had a higher proportion of patients with GHR defects, indicating the presence of Laron syndrome, than patients achieving NAH in the Global IGFD Registry (13).