The identification of a novel mutation of nicotinic acetylcholine receptor gene CHRNB2 in a Chinese patient: Its possible implication in non-familial nocturnal frontal lobe epilepsy.

Autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE) is partly caused by mutations in the nicotinic acetylcholine receptor (nAChR) genes CHRNA4, CHRNB2, and CHRNA2. Cases of non-familial nocturnal frontal lobe epilepsy (NFLE) are more common than the familial type and the phenotypes of the two are similar. CHRNA4 mutations have been found in sporadic NFLE, but no mutation in CHRNB2 or CHRNA2 have been reported. To analyze the genetic features of sporadic NFLE, we designed mutation screening of exon 5 of CHRNA4, exon 5 of CHRNB2, and exon 6 of CHRNA2, mutations in which are associated with ADFLE. We screened a group of 105 Chinese sporadic NFLE cases and identified a novel CHRNB2 mutation, V337G, in an evolutionary conserved region of the intracellular loop between transmembrane domains M3 and M4 in one patient. This mutation was not observed in the control group of 200 subjects. Bioinformatics analysis indicated that the mutation altered the hydrophobicity and secondary structure of the protein. To the best of our knowledge, this study established for the first time that CHRNB2 is potentially associated with non-familial NFLE patient. No mutations in CHRNA4 or CHRNA2 were revealed by our screening method.