Context:The cause of growth impairment in Noonan syndrome (NS) remains unclear. Mutations in PTPN11 (protein tyrosine phosphatase, nonreceptor type 11) that codify constitutively activated Src homology protein tyrosine phosphatase-2 tyrosine phosphatase and may interfere with GH and IGF-I signaling were identified in approximately 40% of patients with NS.Objective: The objective of this study was to evaluate the influence of PTPN11 status on response to human GH (hGH) treatment in NS children with short stature.Setting: This study was performed at a university hospital. Design:The study design was to conduct a retrospective analysis of 3 yr of hGH treatment and genotyping of PTPN11 in patients with NS.Patients: Fourteen NS patients, half of them with PTPN11 mutations in heterozygous state, were studied. At the beginning of treatment, there were no clinical or laboratory differences between groups with and without mutations in the PTPN11 gene. Intervention: Patients were treated with hGH (47 g/kg⅐d). Main Outcome Measures:The main outcome measures were PTPN11 genotype, change in IGF-I levels, and change in height SD score. Results:Patients with mutations in PTPN11 presented a significantly smaller increment in IGF-I levels during the treatment compared with patients without mutations (86 Ϯ 67 and 202 Ϯ 93 g/liter, respectively; P ϭ 0.03). hGH treatment significantly improved growth velocity in both groups, with slightly better results observed in patients without mutations. This was translated into greater gains in height SD score relation to baseline during the 3 yr of treatment in patients without mutations (ϩ1.7 Ϯ 0.1) compared with those with mutations (ϩ0.8 Ϯ 0.4; P Ͻ 0.01). Conclusions

RESUMOIntrodução: Aproximadamente 50% dos pacientes com síndrome de Noonan (SN) apresentam mutações em heterozigose no gene PTPN11. Objetivo: Avaliar a freqüência de mutações no PTPN11 em pacientes com SN e analisar a correlação fenótipo-genótipo. Pacientes: 33 pacientes com SN. Método: Extração de DNA de leucócitos periféricos e seqüenciamento dos 15 exons do P T P N 1 1. R e s u l t a d o s : Nove diferentes mutações m i s s e n s e n o P T P N 1 1, incluindo a mutação P491H, ainda não descrita, foram encontradas em 16 dos 33 pacientes. As características clínicas mais freqüentes dos pacientes com SN foram: pavilhão auricular com rotação incompleta e espessamento da helix (85%), baixa estatura (79%), prega cervical (77%) e criptorquidismo nos meninos (60%). O Z da altura foi de -2,7 ± 1,2 e o do IMC foi de -1 ± 1,4. Os pacientes com mutação no P T P N 1 1 apresentaram maior freqüência de estenose pulmonar do que os pacientes sem mutação (38% vs. 6%, p< 0,05). Pacientes com ou sem mutação no PTPN11 não diferiram em relação à média do Z da altura, Z do IMC, freqüência de alterações torácicas, características faciais, criptorquidia, retardo mental, dificuldade de aprendizado, pico de GH ao teste de estímulo e Z de IGF-1 ou IGFBP-3. Conclusão: Identificamos mutações no PTPN11 em 48,5% dos pacientes com SN, os quais apresentaram maior freqüência de estenose pulmonar. Introduction: Around 50% of Noonan syndrome (NS) patients present heterozygous mutations in the PTPN11 gene. Aim: To evaluate the frequency of mutations in the PTPN11 in patients with NS, and perform phenotype-genotype correlation. Patients: 33 NS patients (23 males). Methods: DNA was extracted from peripheral blood leukocytes, and all 15 PTPN11 exons were directly sequenced. Results: Nine different missense mutations, including the novel P491H, were found in 16 of 33 NS patients. The most frequently observed features in NS patients were posteriorly rotated ears with thick helix (85%), short stature (79%), webbed neck (77%) and cryptorchidism (60%) in boys. The mean height SDS was -2.7 ± 1.2 and BMI SDS was -1 ± 1.4. Patients with PTPN11 mutations presented a higher incidence of pulmonary stenosis than patients without mutations (38% vs. 6%, p< 0.05). Patients with and without mutations did not present differences regarding height SDS, BMI SDS, frequency of thorax deformity, facial characteristics, cryptorchidism, mental retardation, learning disabilities, GH peak at stimulation test and IGF-1 or IGFBP-3 SDS. Conclusion: We identified missense mutations in 48.5% of the NS patients. There was a positive correlation between the presence of PTPN11 mutations and pulmonary stenosis frequency in NS patients. (Arq Bras Endocrinol Metab 2007;51/3:450-456)