ACTL6B and atypical Rett syndrome: The heterogeneity and overlap of symptoms with ID, epilepsy and ASD may have hindered the identification of mutations in BAF53B. An example of this is the eventual identification of the BAF53B homozygous stoploss mutation c.1279delT (p.*427Aspext*32) in a cohort of Rett Syndrome patients (Sajan et al., 2017).