As previously reported in a CDD mouse model carrying a Cdkl5 exon 6 deletion [16,17], we noted, albeit very rarely, the spontaneous occurrence of myoclonic and tonic-clonic seizures in middle-age heterozygous female mice with the Cdkl5 exon 4 deletion (Supplementary Videos 1 and 2). The gene discussed is CDKL5; the disease is craniodiaphyseal dysplasia.