Jacqueline A. Noonan

Noonan syndrome (NS) is a common, clinically and genetically heterogeneous condition characterized by distinctive facial features, short stature, chest deformity, congenital heart disease, and other comorbidities. Gene mutations identified in individuals with the NS phenotype are involved in the Ras/MAPK (mitogen-activated protein kinase) signal transduction pathway and currently explain ∼61% of NS cases. Thus, NS frequently remains a clinical diagnosis. Because of the variability in presentation and the need for multidisciplinary care, it is essential that the condition be identified and managed comprehensively. The Noonan Syndrome Support Group (NSSG) is a nonprofit organization committed to providing support, current information, and understanding to those affected by NS. The NSSG convened a conference of health care providers, all involved in various aspects of NS, to develop these guidelines for use by pediatricians in the diagnosis and management of individuals with NS and to provide updated genetic findings.

AT THE meeting of the Mid-Western Society for Pediatric Research in 1962, I reported on nine patients with remarkably similar facies with a previously unrecognized syndrome of valvular pulmonary stenosis and multiple extra cardiac anomalies.¹Review of the literature at that time showed that several males resembling these patients had been reported under several different headings, most commonly under the designation of, "the male Turner syndrome."^2-5There were no definite reports of similarly affected female patients. In that report I spoke in terms of a "new syndrome" in order to stress that this condition could affect not only males but also females, and that it was also clinically and etiologically different from the true Turner⁶syndrome. Since that time, a further eight patients, five males and three females, with valvular pulmonary stenosis and similar associated lesions have been studied. An additional two patients, one of each sex,