Methods: Study design: The study is a retrospective multi-center chart review study. Data Source(s): All the data will be collected by CRF from inpatient and outpatient electronic medical records in every study site from January 1, 2019 to December 31, 2022. Study Population: Patients who attended the study sites between January 1, 2019 - December 31, 2022 and were diagnosed with NF1 were included in this study. Statistical Analysis: This study is purely descriptive without any formal hypotheses. Missing data for baseline characteristics will be assessed and addressed as a categorical variable with a level for missingness. All reported measures will be summarized in the study tables. Point estimates and their 95% CIs will be presented in the final analyses.