“…RTT has an X-linked dominant pattern of inheritance and mainly affects females with an approximate 1:10,000 incidence featuring predominantly de novo mutations in the methyl-CpG-binding protein 2 (MECP2) gene (Carter et al, 2010;Corchón, Carrillo-López, & Cauli, 2018;Leonard et al, 2017). Phenotype evolution encompasses initial loss of speech and motor skill regression following apparent normal development, with decelerating head growth, hand stereotypies, gait anomalies (ataxia, apraxia), pulmonary dysfunction, mood fluctuation, and disruptive behavior (Munde, Vlaskamp, & Haar, 2016;Wong, Leonard, Jacoby, Ellaway, & Downs, 2015). We present a patient with SSADHD and RTT, disorders typically associated with autism spectrum disorder and epilepsy (Benke & Möhler, 2018;Frye et al, 2016).…”