We also identified variants in genes that are linked to neurological syndromes, such as MECP2, CDKL5, GRIN2A, SCN1A, PCDH19, UBE3A, and SLC9A6. Developmental regression is frequently seen in patients with Rett Syndrome, Landau Kleffner Syndrome, and Christianson Syndrome. The gene discussed is SLC9A6; the disease is atypical Rett syndrome.