Because of the link between SMC5/6 perturbation and neurodevelopmental disorders in humans (Homsy et al., 2015; Jin et al., 2017; Landrum et al., 2018; Payne et al., 2014), we modeled the consequences of SMC5/6 depletion by conditionally mutating Smc5 in the developing neocortex of mice. This evidence concerns the gene SMC5 and neurodevelopmental disorder.