<prompt> A male child presented with cryptorchidism, mental retardation and pulmonary stenosis. He has normal karyotype. Which of the following is the diagnosis?Noonans syndromeTurners syndromeDowns syndromeAngelmanns syndrome  <response>: The karyotype is normal and it is a male child so the diagnosis is Noonans syndrome. Noonan syndrome have normal karyotypes and it is an impoant distinction with Turners 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. 