A child presents with antimongoloid slant, pulmonary stenosis, sho stature, and undescended testis. The likely diagnosis is _____: (A) Hypoparathyroidism, (B) Noonan syndrome, (C) Klinefelter syndrome, (D) XYY sex chromosome
Answer is B. The child presenting with the antimongoloid slant, pulmonary stenosis, sho stature, and undescended testis is suggestive of Noonan syndrome. Noonan syndrome: Autosomal-dominant disorder (12q) Male or female with Turner phenotype; normal karyotype Clinical features: Down-slanting palpebral fissure (antimongoloid slant) Pectus carinatum Hypeelorism Cryptorchidism Low levels of clotting factor 11 and 12 Leukemia (Juvenile chronic myelogenous leukemia) Moderate mental retardation in 25% Cardiac abnormality: Most common is pulmonary valve stenosis Hyperophic cardiomyopathy Atrial septal defect Coarctation of aoa Sho stature, webbed neck, low set ears, cubitus valgus: Similarities with Turner syndrome Ptosis, micrognathia, Clinodactyly, delayed pubey Difference between Noonan syndrome and Turner&;s syndrome: Noonan syndrome Turner Syndrome Normal karyotype (46XX/46XY) 45,XO(60%) Most common hea disease: Valvular pulmonary stenosis Most common hea disease: Bicuspid aoic valve 25% have mental retardation Mental retardation rare Genitourinary: Genitourinary: Female: Feile, delayed pubey Female: Infeile, Streak ovaries Male: Infeile due to cryptorchidism No males Ref: nelson textbook of pediatrics 21st edition Pgno: 669,2995