A male child presented with cryptorchidism, mental retardation and pulmonary stenosis. He has normal karyotype. Which of the following is the diagnosis?

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.