To measure this defect, we stained mature neurons with NeuN (RBFOX3) and quantified the number of bi-nucleated neurons in the neocortex of brain.The proportion of multinucleated neurons expressing NeuN in the cortical region of Cep55-/- mice was increased compared to that of Cep55+/+ (S2D and S2E Fig), a phenotype reminiscent of the described changes in human embryos with MARCH syndrome [6]. Here, RBFOX3 is linked to multinucleated neurons-anhydramnios-renal dysplasia-cerebellar hypoplasia-hydranencephaly syndrome.