Wdr26 insufficiency causes Skraban-Deardorff syndrome-like neurodevelopmental deficits in mice

Skraban-Deardorff syndrome, a rare neurodevelopmental disorder caused by WD repeat domain 26 (WDR26) haploinsufficiency, is characterized by intellectual disability, seizures, autistic-like behaviors, and craniofacial anomalies. Despite its genetic association with variants disrupting the C-terminal to LisH (CTLH) E3 ubiquitin ligase complex, the molecular mechanisms linking WDR26 dysfunction to neurodevelopmental deficits remain unclear. Here, we demonstrate that Wdr26 heterozygous-KO mice (Wdr26+/-) recapitulated core clinical features of the syndrome, including learning and memory impairments, social dysfunction, heightened seizure susceptibility, and motor deficits, alongside rare craniofacial and dental abnormalities. Mechanistically, Wdr26 haploinsufficiency stabilized RUNX1 translocation partner 1 (RUNX1T1), a transcriptional coactivator critical for neuronal differentiation, by impairing its ubiquitination and proteasomal degradation, consequently disrupting the level of microtubule-associated protein 2 (MAP2), a key regulator of dendritic architecture and synaptic plasticity. Early intervention in neonatal Wdr26+/- mice (P0.5) using AAV-shRNA-mediated Runx1t1 knockdown reversed MAP2 overexpression and behavioral deficits. Notably, the antipsychotic risperidone ameliorated cognitive and social impairments in Wdr26+/- mice by upregulating WDR26 levels, suggesting a potential therapeutic avenue. Our findings not only establish the animal model as a robust preclinical tool but also define the WDR26/RUNX1T1/MAP2 regulatory axis as pivotal to the syndrome's pathogenesis, while identifying actionable therapeutic targets.