Nicotinic receptor channelopathies and epilepsy

Characterized by sudden episodes called seizures, epilepsy was recognized long ago as a neurological disorder that can have multiple forms ranging from benign to life threatening depending upon its severity. Although several evidences indicated that genes play an important role in at least half of the patients, it is only with the advances in molecular biology and genetics that the puzzle about oligogenic and monogenic epilepsies slowly starts to unfold. The finding of an association between a monogenic form of epilepsy and a mutation in the gene encoding the neuronal nicotinic acetylcholine receptor subunit CHRNA4 marked, in 1995, a turning point in our understanding of epilepsy. It also marked the first step towards the today widely acknowledged concept of epilepsies as channelopathies. Several mutations in nicotinic acetylcholine receptor genes have, since then, been identified, and the functional properties of these mutated receptors were characterized. In this work, we review, in the light of the latest discoveries, the effects caused by the mutations on the physiological properties of the receptors and the impact of such mutations on neuronal network functions.