Epilepsy is a frequent neurological disease in childhood, characterized by recurrent seizures and sometimes with major effects on social, behavioral and cognitive development. Childhood focal epilepsies particularly are age-related diseases mainly occurring during developmental critical period. A complex interplay between brain development and maturation processes and susceptibility genes may contribute to the development of various childhood epileptic syndromes associated with language and cognitive deficits. Indeed, the Landau-Kleffner syndrome (LKS), the continuous spike-and-waves during sleep syndrome (CSWS), and the benign childhood epilepsy with centrotemporal spikes (BCECTS) or benign rolandic epilepsy, are different syndromes that are considered as part of a single continuous spectrum of disorders. While genetic component in those three syndromes remains elusive, novel and high throughput genome analyzes could bring interesting insights into the possible genetic defects and pathophysiological mechanisms underlying and linking the various disorders associating epilepsy with speech and cognitive impairments.