Insulin-like growth factor-I treatment in two children with growth hormonegene deletions

Two unrelated Brazilian patients had homozygous 6.7 kb deletions in the GH- 1 gene (girl and boy, 1.8 and 3.3 yr, heights -7.9 and -6.0 SDS, respective ly). Desensitization using small amounts of exogenous GH (0.033 IU/kg body weight/week, divided into daily s.c. injections) was attempted, but anti-GH antibodies appeared. Replacement with usual doses of hGH induced only tran sient increase in growth. IGF-I therapy with increasing doses resulted in c atch-up growth without side-effects. Growth velocity was 7.5 cm/yr in the f irst year and 8.4 cm/yr in the next 6 months in patient 1, and 6.7 cm/yr in the first year, 5.9 cm/yr in the second year and 7.9 cm/yr in the third ye ar of IGF-I treatment in patient 2, when the daily dose of 240 mu g/kg was divided into three injections. IGFBP-3 levels were low (0.55 and 0.40 mg/l) and did not increase after IGF-I treatment, suggesting that this GH effect is not mediated by IGF-I, and injected IGF-I had a rapid disappearance rat e, We conclude that IGF-I promotes growth by endocrine mechanisms and const itutes an effective treatment for patients with GH insensitivity secondary to GH antibodies.