ESPE Abstracts

Introduction: Noonan syndrome (NS) is a rare autosomal dominant genetic disorder with an estimated incidence of 1/2500. Diagnosis is mainly clinical, with the association of dysmorphic signs, cardiac malformations and delayed growth.

Observation: The cases involved 2 boys and 2 girls. The average age at diagnosis was 9.5 years, with a characteristic facial dysmorphia in 100% of cases, cardiac malformations such as pulmonary narrowing in both boys, tetralogy of Fallot in one girl and atrioventricular canal in the other. Statural retardation in all 4 patients, severe at less than 3 SD in 75%, with delayed language acquisition in 50%, and conductive deafness in one patient. Hormonal assessment revealed low IGF1 levels in 75%, and a GH stimulation test was performed in both girls, ruling out GH deficiency. GH treatment was initiated in two cases at a dose of 0.035 mg/kg. One patient gained 12.5cm in 18 months, the other 4cm in 08 months.

Discussion: Clinical manifestations suggestive of SN are common to other syndromes, and may lead to delayed diagnosis. Growth retardation affects 70-80% of patients, with GH deficiency (rarely complete), neuro-secretory dysfunction or resistance. Response to treatment varies according notably to the mutation involved (PTPN11 mutations).