From OMIM
Focal epilepsy with speech disorder is a childhood-onset seizure disorder with a highly variable phenotype. Seizures typically occur in the temporal lobe, or rolandic brain region, which affects speech and language, and electroencephalogram (EEG) characteristically shows centrotemporal spike-wave discharges. EEG abnormalities often occur during sleep and may manifest as continuous spike-wave discharges during slow-wave sleep (CSWS or CSWSS). FESD represents an electroclinical spectrum that ranges from severe early-onset seizures associated with delayed psychomotor development, persistent speech difficulties, and impaired intellectual development to a more benign entity characterized by childhood onset of mild or asymptomatic seizures associated with transient speech difficulties followed by remission of seizures in adolescence and normal psychomotor development. There is incomplete penetrance and intrafamilial variability, even among family members who carry the same GRIN2A mutation (summary by Lesca et al., 2013; Lemke et al., 2013; Carvill et al., 2013). The disorder represented here encompasses several clinical entities, including Landau-Kleffner syndrome (LKS), epileptic encephalopathy with continuous spike and wave during slow-wave sleep (ECSWS; CSWSS), autosomal dominant rolandic epilepsy, impaired intellectual development, and speech dyspraxia (ADRESD; RESDAD), and benign epilepsy with centrotemporal spikes (BECTS; see 117100). LKS is classically described as a childhood-onset variant of epileptic aphasia. It is associated with EEG abnormalities occurring in the temporal lobe of the language-dominant hemisphere, even in the absence of overt clinical seizures. LKS is sometimes referred to as an 'acquired aphasia' because most affected children show normal psychomotor development until the onset of seizures, usually between 3 and 7 years, although some may have prior delayed development. A hallmark of the disorder is severe impairment in auditory language comprehension and speech. Some patients may also have persistent intellectual disability or behavioral abnormalities reminiscent of autism or attention deficit-hyperactivity disorder. EEG abnormalities typically include centrotemporal spikes suggestive of rolandic epilepsy or continuous spike and waves during slow-wave sleep. The presence of CSWS is associated with more widespread behavioral and cognitive regression than LKS, although the 2 disorders may be considered part of a spectrum. There is controversy about the precise definition of LKS and its relationship to CSWS that stems mainly from the phenotypic heterogeneity of the disorder (summary by Stefanatos, 2011).  http://www.omim.org/entry/245570