BACKGROUND

Noonan syndrome (NS) and Noonan-like syndrome with loose anagen hair (NS/LAH) are neurodevelopmental syndromes resulting from germline mutations in genes that participate in the rat sarcoma/mitogen-activated protein kinases (RAS/MAPK) pathway. The aim of this retrospective study was to describe common and rare manifestations of NS and NS/LAH.

METHODS

We collected and analyzed clinical and genetic data from 25 patients with NS and NS/LAH.

RESULTS

The patients' median age was 6.3 years (range, 1-13 years), and the male-to-female ratio was 18:7. In total, 19 patients had NS caused by a mutation in . Another causative gene was found in six patients, including two patients with a mutation, one patient with a KRAS mutation, one patient with an mutation, one patient with a mutation, and one patient with a PPP1CB mutation. Short stature was detected in 100% of the patients. This study provides an overview of the clinical features of NS, including unique facial features, short stature, congenital heart defects, and other manifestations. Notably, systemic lupus erythematosus (SLE) was found in two -positive patients. One patient had a posterior urethral valve, which is very rare in NS patients.

CONCLUSIONS

Our study identified several clinical features that were previously poorly related to NS, including SLE. We concluded that -related NS is associated with a particularly high risk of SLE, which may have a significant impact on quality of life, and a posterior urethral valve is a novel phenotype. These findings could be helpful in enhancing the understanding of the clinical spectrum of NS.