Update on the genetics of the epilepsy-aphasia spectrum and role of GRIN2A mutations.

Formerly idiopathic, focal epilepsies (IFE) are self-limiting, "age-related" diseases that mainly occur during critical developmental periods. Childhood epilepsy with centrotemporal spikes, or Rolandic epilepsy (RE), is the most frequent form of IFE. Together with the Landau-Kleffner syndrome and the epileptic Encephalopathy related to Status Epilepticus during slow Sleep syndrome (ESES), RE is part of a single and continuous spectrum of childhood epilepsies and epileptic encephalopathies with acquired cognitive, behavioral and speech and/or language impairment, known as the epilepsy-aphasia spectrum (EAS). The pathophysiology has long been attributed to an elusive and complex interplay between brain development and maturation processes on the one hand, and susceptibility genes on the other hand. Studies based on the variable combination of molecular cytogenetics, Sanger and next-generation sequencing tools, and functional assays have led to the identification and validation of genetic mutations in the GRIN2A gene that can directly cause various types of EAS disorders. The recent identification of GRIN2A defects in EAS represents a first and major break-through in our understanding of the underlying pathophysiological mechanisms. In this review, we describe the current knowledge on the genetic architecture of IFE.

Epilepsy as a derailment of sleep plastic functions may cause chronic cognitive impairment - A theoretical review.

We report on a peculiar way of chronic cognitive impairment associated with interictal epileptic activity during NREM sleep. We review three major groups of epilepsy: mesiotemporal epilepsy (MTLE) involving the epileptic derailment of the hippocampal declarative memory system; childhood developmental epileptic encephalopathies; and the spectrum disorders of the perisylvian communication network with the centrotemporal spike phenomenon, overarching child- and adulthood epilepsies, totaling up the majority of epilepsies in childhood. We outline high impact research-lines on the cognitive harm of epilepsy; causing specific or global cognitive decline through its interference with sleep plastic functions. We highlight the key role of interictal activity in the development of cognitive impairment and the fact that we are unarmed against this harm, antiepileptic pharmaco-therapy being ineffective against the interictal process marked by spikes and high frequency oscillations.