Autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE) can be caused by mutations in the neuronal nicotinic acetylcholine receptor (nAChR) subunit genes CHRNA4 and CHRNB2. Recently, a point mutation (alpha2-I279N) associated with sleep-related epilepsy has been described in a third nAChR gene, CHRNA2. We demonstrate here that alpha2-I279N can be co-expressed with the major structural subunit CHRNB2. alpha2-I279N causes a marked gain-of-function effect and displays a distinct biopharmacological profile, including markedly reduced inhibition by carbamazepine and increased nicotine sensitivity.