Genetic testing has greatly advanced diagnosis of early onset epilepsy. In spite of the expanding number of monogenetic disorders, such as epilepsy in patients with Aristaless-related homeobox gene (ARX) mutations, many of these rare diseases do not have a validated experimental model and thus suffer from limited understanding of the mechanisms of brain development and epileptogenesis. ARX is a transcription factor which is widely expressed in the developing and adult brain, skeletal muscle, pancreas, and testes.