Noonan syndrome.

Abstract

Noonan syndrome was first described over 20 years ago by Noonan and Ehmkel; they defined a specific group of nine patients with valvular pulmonary stenosis who, in addition, had short stature, mild mental retardation, hypertelorism, and unusual facies. In retrospect, the first case was probably described by Kobylinski in 1883.2 Since that time, over 300 cases have been reported in medical publications. The incidence of Noonan syndrome has been estimated to be between 1 in 1000 and 1 in 2500 live births.3 The cardinal features of Noonan syndrome are short stature, congenital heart defect, broad or webbed neck, a peculiar chest deformity with pectus carinatum superiorly and pectus excava- tum inferiorly, and characteristic facies, which alter predictably with age to produce a discrete but changing phenotype which is described and illus- trated below. Good reviews of Noonan syndrome are to be found by Mendez and Opitz,4 Nora et al,5 Char et al,6 and Pearl.7