Knowra Noonan syndrome Noonan syndrome Noonan syndrome is a genetic condition that affects growth and development and often involves distinctive facial features, short stature, congenital heart defects, and variable learning differences. It belongs to a group of disorders caused by altered RAS–MAPK signaling.
RAS–MAPK pathway : A cell-signaling network that regulates growth, division, differentiation, and survival. Noonan syndrome arises when variants disrupt this pathway’s control of development.
Hypertrophic cardiomyopathy : A disease in which the heart muscle becomes abnormally thick, sometimes obstructing blood flow. It is a potentially serious cardiac complication, especially in some gene-associated forms.
Autosomal dominant inheritance : An inheritance pattern in which one altered gene copy can cause a condition. Many cases follow this pattern, though a new variant is common and severity varies.
Turner syndrome : A chromosomal condition in females caused by complete or partial absence of one X chromosome. Short stature and heart defects can resemble Noonan syndrome, but the genetic cause differs.
Jacqueline Noonan : An American pediatric cardiologist who described the syndrome in children with congenital heart disease and distinctive features. Her clinical description established the recognizable syndrome later named for her.
PTPN11 : A gene encoding SHP-2, a signaling protein that helps regulate the RAS–MAPK pathway. Variants in PTPN11 account for a large share of Noonan syndrome diagnoses.
Pulmonary valve stenosis : A narrowing at or near the valve that carries blood from the heart to the lungs. It is among the most characteristic congenital heart defects in Noonan syndrome.
De novo mutation : A genetic change that first appears in an individual rather than being inherited from a parent. Many people with Noonan syndrome have a variant absent from both parents.
Cardiofaciocutaneous syndrome : A RASopathy involving characteristic cardiac, facial, skin, and developmental findings. It overlaps clinically with Noonan syndrome but often has more pronounced skin and developmental features.
Alois J. Schinzel : A Swiss geneticist who contributed to the clinical characterization of Noonan syndrome. His work helped define the syndrome’s broad and variable clinical presentation.
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