Objectives: To discuss the genotype/phenotype correlation of eight cases with pathogenic variant in the PTPN11 gene. Materials and Methods: Eight cases with a prediagnosis of Noonan Syndrome, in which the PTPN11 gene sequence analysis was performed between 2017 and 2019 at Karadeniz Technical University Faculty of Medicine and Trabzon Kanuni Training and Research Hospital, Department of Medical Genetics were retrospectively evaluated in the study. Results: The most common findings in the eight cases with pathogenic variant in the PTPN11 gene were heart defect (87.5%), short stature (87.5%), and low-set posteriorly rotated ears (87.5%) and the most common heart defect was pulmonary stenosis (62.5%). The clinical diagnoses of those cases were Noonan Syndrome (87.5%) and Noonan syndrome with multiple lentigines (12.5%). NM_002834.5: PTPN11; c.922A>G; p.Asn308Asp mutation was the most commonly (25%) detected mutation. Conclusion: The phenotypes caused by all disease-causing variants found in this study were detected to be compatible with the current knowledge. Pathogenic variants of PTPN11 are responsible for 50% of RASopathies, and PTPN11 sequence analysis is a cost-effective method in patients with normal karyotyping, meeting the scoring system for Noonan Syndrome with clinical findings.