Noonan syndrome: molecular and clinical findings in individuals with PTPN11 pathogenic variants

Purpose: RASopathies encompass a spectrum of disorders resulting from pathogenic variants in genes associated with the Ras/mitogen-activated protein kinase (RAS/MAPK) pathway, critical for cellular functions like proliferation, differentiation and survival. Noonan syndrome (NS), the most prevalent form of RASopathies, presents with a myriad of clinical features including characteristic facial dysmorphisms, congenital heart defects, and developmental delays. Despite its clinical recognition, molecular confirmation remains elusive in a notable percentage of cases. In this study, we aimed to investigate the clinical and molecular profiles of six patients diagnosed with NS, focusing on the role of PTPN11 gene mutations. Materials and methods: Molecular evaluation was performed using PTPN11 gene sequence analysis and whole gene sequencing methods in six patients who were thought to have typical NS phenotypes based on clinical evaluations. Results: Molecular screening in patients identified four different pathogenic variants in the PTPN11 gene. These variants, all heterozygous, were classified as pathogenic according to established criteria. Conclusion: Our findings contribute to understanding the genetic landscape of NS and underscore the significance of molecular analysis in confirming diagnoses.