CDKL5 and atypical Rett syndrome: To determine if elevated DNA damage is potentially a trigger of Rett syndrome phenotypes irrespective of the nature of the mutation, we also assessed isogenic neurons from hiPSCs derived from patients with Rett syndrome caused by mutations in CDKL5 (Fuchs et al., 2014; Jagtap et al., 2019; Loi et al., 2020; Negraes et al., 2021).