Insulin-like growth factor-1 (IGF-1) is the main driver of growth during prenatal life and acts through IGF-1 receptor (IGF1R). Patients with IGF1R defects exhibit variable phenotypic features. A 10.9-year-old boy presented with severe short stature, microcephaly, minor dysmorphic features and mental retardation. Genetic analysis for IGF1R revealed heterozygous deletion of the complete IGF1R. At the age of 12.3 years, daily subcutaneous recombinant human growth hormone (rhGH) was started and continued for a total of 5.7 years in two courses with improvement of height velocity as well as final height. Puberty was delayed and eventually he did not achieve full puberty, suggesting partial hypogonadotropic hypogonadism. Hypothyroidism initially developed during rhGH therapy. However, low T4 levels persisted after cessation of rhGH therapy and thus central hypothyroidism is a likely diagnosis. rhGH has partial effect for induction of growth in cases with IGF1R defects. However, long-term treatment with an early initiation may have more beneficial effects. In addition, patients with IGF1R defects should be followed for delayed puberty-hypogonadism, and hypothyroidism.
