ARX and Epileptic encephalopathy: A mutation in the splice acceptor site at the 3′ end of intron 4, ARX:c.1449-1 G > C, has been reported in a boy with early-onset developmental and epileptic encephalopathy, and this mutation was also predicted to abolish the splice acceptor site, retaining intron 4 and leading to a premature termination codon immediately after exon 410.