Many patients are, at least initially, not aware of their seizures, or they underestimate their number of seizures per night. Typical compiaints are tiredness during daytime and poor sleep quality. Treatment with antiepileptic drugs such as carbamazepine is effective with respect to seizure control or reduction in many, but not all, patients.4 In 1995 a first mutation was identified in the CHRNA4 gene as the underlying cause in a large Australian ADNFLE family that previously helped to map the disorder to chromosome 20q13.3.5 Since then, additional CHRNA4 mutations, as well as mutations in two additional gènes (CHRNB2, CHRNA2), hâve been found Inhibitors,research,lifescience,medical in sleep-relatcd frontal

lobe epilcpsy.6-8 CHRNA4, CHRNA2, and CHRNB2 encode the α4- and β2-subunits of the neuronal nicotinic acetyleholine receptor (nAChR), respectively.

Inhibitors,research,lifescience,medical The nAChRs are members of the large family of lig-and-gated ion channels. They are characterized by five (identical or different) homologous subunits that assemble around a central axis and form a cation-selective ion channel. With the exception of CHRNB2-I312M the known ADNFLE mutations in more either CHRNA4 or CHRNB2 are located within the second transmembrane domain. The second transmembrane (and in parts Inhibitors,research,lifescience,medical the third) domain mainly builds the walls of the ion channel; thus, it seems that ADNFLE mutations specifically target the channel’s gating structure. Until now, four CHRNA4 and three CHRNB2 mutations have been described in ADNFLE families from different Inhibitors,research,lifescience,medical parts of the world. Most interesting arc those mutations that have occurred independently

in different families, because they offer the opportunity to study the effects genetic backgrounds might have on the clinical expression Inhibitors,research,lifescience,medical of the disorder.9 Not surprisingly in view of the important role of the cholinergic System in higher brain functions, there has been evidence presented that at least some ADNFLE mutations not only cause epilepsy but are also associated with other neurological disorders or cognitive Cilengitide deficits. A good example is presented by the Norwegian ADNFLE family carrying the CHRNA4-776ins3 mutation.10,11 More than half of the 11 mutation carriers are affected by either schizophrenia, negative symptoms of schizophrenia, or severe apathy. Another ADNFLE mutation, CHRNA4-S252L, is associated with mental retardation and/or behavioral problems in two families of different geographic origin. In the latter families the differences in geographic origin strongly suggest that the cognitive deficits are caused by the mutation rather than by unrelated factors.8 Most of the known ADNFLE mutations have already been studied in different expression systems. They typically display an increased sensitivity for the natural agonist acetylcholine, demonstrated by a shift of the agonist response curve to the left.