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 […]