Abstract: Objective　To explore the clinical and genetic characteristics of Noonan syndrome in children. Methods The clinical data of Noonan syndrome in 7 children diagnosed from January to December 2018 were collected. Familial analysis and interpretation were completed by whole exon sequencing and Sanger sequencing. Results　Four boys and 3 girls visited the clinic for their short stature and the median age of diagnosis was 3 years and 3 months (8 months to 13 years and 1 month). Six children had characteristic features of Noonan syndrome, such as pigmentation, curly hair, webbed neck, palmthrough, scoliosis and cryptorchidism. Six children had mental retardation. Four children had a peak GH concentration>10 ng/ mL in provocation test, and there was no abnormality of insulin-like growth factor. Abnormal cardiac structure was founded in 5 cases, including 2 cases of pulmonary stenosis, 2 cases of atrial septal defect, one case of mitral insufficiency and one case of hypertrophic ventricular septal. Missense mutations of PTPN11 gene were found in all 7 children, including 6 de novo mutations and one paternal mutation, and all these mutations were considered to be pathogenic according to the ACMG Practice Guideline. Conclusions　Growth failure is the main presentation in patients with Noonan syndrome. Short stature, special facial features and mental retardation are common manifestations. Many cardiovascular phenotypes occur in Noonan syndrome. Noonan syndrome is caused by missense mutations in PTPN11, mainly de novo mutation.

Key words: Noonan syndrome;　clinical phenotype;　PTPN11 gene