Clinical, Electrophysiological, and Genetic Analysis in a Family with Autosomal Dominant Nocturnal Frontal Lobe Epilepsy

ABSTRACT

BACKGROUND: Autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE) is a distinct epilepsy syndrome and a genetically heterogeneous disorder linked to chromosomes 20q13.2, 15q24, and 1p21. Missense and insertion mutations in neuronal nicotine acetylcholine receptor 4 (CHRNA4) and 2 (CHRNB2) genes have been found in families with ADNFLE. METHODS: Clinical, EEG-Video monitoring, and neuropsychologic study in a family with ADNFLE were tested. For detect of mutation gene, polymerase chain reaction for CHRNA4 gene and CHRNB2 gene, single strand conformational polymorphism (SSCP) analysis and DNA sequencing were done. RESULTS: Among 15 living family members in three generations, nine had seizures. EEG-Video monitoring showed ictal epileptiform discharges genetically or regionally in frontal, frontocentral, frontotemporal, or temporal areas and less frequently no epileptiform discharges or non-specific generalized slowing. Two affected individuals demonstrated interictal temporal spikes, whereas the others were normal. Neuropsychological study showed mental retardation and decreased frontal executive function in five affected individuals. A cytosine to thymine exchange (755C>T; S252L) in exon 5 of the CHRNA4 gene was found on all affected individuals except in an individual who wasn 't tested, but this change was absent in those without epilepsy. CONCLUSIONS: This is the first study of genetically confirmed ADNFLE in a Korean family, who had mental retardation and various EEG abnormalities, ictally and interictally.