Concomitant Mosaic Turner Syndrome and Congenital Adrenal Hyperplasia in 1 of 3 Patients of USP9X Variant-Associated Autism Spectrum Disorder.

Introduction: X-linked intellectual developmental disorder 99 (XLID99) is a rare neurodevelopmental disorder associated with mutations in the USP9X gene. This study reports on 3 patients diagnosed with autism spectrum disorder (ASD), highlighting novel genetic findings. Case Presentation: Among the 3 patients, two male siblings exhibited a novel USP9X gene missense variant, while the third, a female, presented a unique deletion of the USP9X gene alongside adrenal insufficiency and mosaic Turner syndrome. This variant has not been reported in public databases and may influence ASD development. Conclusion: This report documents the first instance of a triple diagnosis of XLID99, Turner syndrome, and congenital adrenal hyperplasia. Findings underline the significance of genetic evaluation in ASD for identifying rare and complex diagnoses.