Notably, these variants were identified in genes including CDH15 (mental retardation), GATAD2B (mental retardation), SEMA3E (CHARGE syndrome), PDE4D (Acrodysostosis 2, with or without hormone resistance), SHROOM4 (Stocco dos Santos X-linked mental retardation syndrome), DLG3 (mental retardation), and ERE (neurodevelopmental disorder), all of which were believed to be potentially novel ASD candidate genes but lack previous association with ASD in major genomic databases. Here, PDE4D is linked to CHARGE syndrome.