Ohtahara syndrome or Early Infantile Epileptic Encephalopathy (EIEE) with 
Suppression-Burst, is the most severe and the earliest developing age-related 
epileptic encephalopathy. Clinically, the syndrome is characterized by early 
onset tonic spasms associated with a severe and continuous pattern of burst 
activity. It is a debilitating and early progressive neurological disorder, 
resulting in intractable seizures and severe mental retardation. Specific 
mutations in at least four genes (whose protein products are essential in lower 
brain's neuronal and interneuronal functions, including mitochondrial 
respiratory chains have been identified in unrelated individuals with EIEE and 
include: (a) the ARX (aristaless-related) homeobox gene at Xp22.13 (EIEE-1 
variant); (b) the CDKL5 (SYK9) gene at Xp22 (EIEE-2 variant); (c) the SLC25A22 
(GC1) gene at 11p15.5 (EIEE-3 variant); and (d) the Stxbp1 (MUNC18-1) gene at 
9q34-1 (EIEE-4 variant). A yet unresolved issue involves the relationship 
between early myoclonic encephalopathy (EME-ErbB4 mutations) versus the EIEE 
spectrum of disorders.