Definition of NS

NS: Noonan syndrome, a multifaceted condition characterized by a series of birth defects (congenital malformations) including short stature after birth (postnatal growth retardation), webbing of the neck (pterygium colli), caved-in chestbone (pectus excavatum), narrowing of the artery from the heart to the lungs (pulmonic stenosis) and, in boys, testes that do not descend normally into the scrotum (cryptorchidism).

Although NS was called Turner-like syndrome, it is a distinctive entity that affects both sexes and carries an elevated risk of developmental and language delay, learning disability, hearing loss, and mild mental retardation. NS is inherited as a dominant condition and an NS gene has been mapped to chromosome12.