Long-term GH treatment improves adult height in children with Noonan syndrome with and without mutations in protein tyrosine phosphatase, non-receptor-type 11.

CONTEXT Noonan syndrome (NS) is characterized by short stature, typical facial dysmorphology and congenital heart defects. Short-term effect of GH therapy in NS is beneficial, reports on the effect on adult height are scarce. OBJECTIVE To determine the effect of long-term GH therapy in children with NS. DESIGN Twenty-nine children with NS were treated with GH until final height was reached. SETTING Hospital endocrinology departments. PATIENTS Children with the clinical diagnosis of NS, with mean age at the start of therapy of 11.0 years, 22 out of 27 tested children had a mutation in the protein tyrosine phosphatase, non-receptor-type 11 gene (PTPN11 gene). Interventions GH was administered subcutaneously at 0.05 mg/kg per day until growth velocity was 1 cm/6 months. MAIN OUTCOME MEASURE Linear growth (height) was measured at 3-month intervals in the first year and at 6-month intervals thereafter until final height. RESULTS At the start of treatment, median height SDS (H-SDS) was -2.8 (-4.1 to -1.8) and 0.0 (-1.4 to +1.2), based on national and Noonan standards respectively. GH therapy lasted for 3.0-10.3 years (median, 6.4), producing mean gains in H-SDS of +1.3 (+0.2 to +2.7) and +1.3 (-0.6 to +2.4), based on national and Noonan standards respectively. In 22 children with a mutation in PTPN11 mean gain in H-SDS for National standards was +1.3, not different from the mean gain in the five children without a mutation in PTPN11+1.3 (P=0.98). CONCLUSION Long-term GH treatment in NS leads to attainment of adult height within the normal range in most patients.