Facial Phenotype of Noonan Syndrome

Core Ocular Features

Hypertelorism (widely spaced eyes) occurs in approximately 31 %–100 % of individuals with Noonan syndrome, making it one of the most consistent ocular findings. 1
Downslanting palpebral fissures are a hallmark ocular characteristic of Noonan syndrome. 1
Ptosis (drooping of the upper eyelids) is frequently observed in affected individuals. 1
Epicanthal folds are commonly present, especially during infancy. 1

A short nose with a broad nasal base and bulbous tip is characteristic of the syndrome. 1

Ears are typically low‑set, posteriorly rotated, and display a thickened helix; they often appear posteriorly angulated. 1

A broad forehead with bitemporal narrowing is reported in some phenotypic variants. 1
Relative macrocephaly is a common cranial finding. 1

In infancy, individuals commonly exhibit full cheeks and a flat facial profile. 2
Epicanthal folds are more prominent during the infant period. 2
During adolescence and adulthood, the face may become narrower and a longer neck often develops. 2
Overall facial features tend to become less pronounced with increasing age. 1

Compared with Cardio‑Facio‑Cutaneous (CFC) syndrome and Costello syndrome, Noonan syndrome displays less coarse facial features, aiding clinical distinction. [1][3]
Cutaneous manifestations such as follicular hyperkeratosis are less frequent in Noonan syndrome than in CFC syndrome. [1][3]
Eyebrows are less sparse in Noonan syndrome relative to CFC syndrome. 1
The incidence of ulerythema ophryogenes is lower in Noonan syndrome compared with CFC syndrome. 1

Recognition of the characteristic facial phenotype is critical for early diagnosis, often serving as the first clue when combined with cardiac anomalies, feeding difficulties, or developmental delay. [1][3]