A male child presented with cryptorchidism, mental retardation and pulmonary stenosis. He has normal karyotype. Which of the following is the diagnosis?
Noonan's syndrome
Turner's syndrome
Down's syndrome
Angelmann's syndrome
The karyotype is normal and it is a male child so the diagnosis is Noonan's syndrome. Noonan syndrome have normal karyotypes and it is an impoant distinction with Turner's syndrome. Mutations in the RAS-MAPK signaling pathway are responsible for Noonan syndrome. The cardinal features of Noonan syndrome include unusual facies (ie, hypeelorism, down-slanting eyes, and webbed neck), congenital hea disease (in 50%), sho stature, and chest deformity. Approximately 25% of individuals with Noonan syndrome have mental retardation. Bleeding diathesis is present in as many as half of all patients with Noonan syndrome.