Pathogenic XPO1 variants cause a dominant neurodevelopmental disorder

Purpose: XPO1 functions in key cellular processes, including nucleo-cytoplasmic export and mitosis. The gene is deleted in a subset of patients with the 2p15p16.1 microdeletion syndrome; however, no monogenic XPO1-related disorder has been described to date. Methods: We collected clinical data of individuals with de novo XPO1 variants through online matchmaking. We used Drosophila to study XPO1 function in development and habituation learning. Results: A total of 22 individuals met the criteria to be included in the main study cohort. Of these, half have putative loss-of-function variants, and half have coding variants (10 missense and 1 in-frame deletion variant). We found an overlapping phenotype, consistent with a monogenic neurodevelopmental disorder. We demonstrate XPO1 functions in development by ubiquitous and neuron-specific knockdown in Drosophila. GABAergic neuron specific knockdown flies demonstrated impaired habituation. Conclusion: Our results establish XPO1 as a novel dominant monogenic neurodevelopmental disorder gene and demonstrate a central role for XPO1 in development.