Rett syndrome (RTT) (OMIM ID: 312750) is a severe progressive neurological disorder usually linked to two major X-linked gene mutations, that is, methyl-CpG binding protein 2 gene (MECP2) and cyclin-dependent kinase-like 5 (CDKL5) [1–3]. Here, CDKL5 is linked to atypical Rett syndrome.