1. A splice-site mutation in GABRG2 associated with childhood absence epilepsy and febrile convulsions
- Author
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Kerstin Hallmann, Ortrud K. Steinlein, Uwe Runge, Johannes Rebstock, Armin Heils, Colette Kananura, Wenli Gu, Karsten Haug, and Thomas Sander
- Subjects
Male ,Adolescent ,Genotype ,Population ,Mutation, Missense ,Biology ,Seizures, Febrile ,Idiopathic generalized epilepsy ,Epilepsy ,Childhood absence epilepsy ,Arts and Humanities (miscellaneous) ,medicine ,Missense mutation ,Humans ,education ,Alleles ,Genetics ,education.field_of_study ,Splice site mutation ,Polymorphism, Genetic ,Reverse Transcriptase Polymerase Chain Reaction ,Point mutation ,Exons ,medicine.disease ,Receptors, GABA-A ,Epilepsy, Absence ,Epilepsy syndromes ,Female ,Neurology (clinical) - Abstract
Context Missense mutations in the GABRG2 gene, which encodes the γ2 subunit of central nervous γ-aminobutyric acid (GABA) A receptors, have recently been described in 2 families with idiopathic epilepsy. In one of these families, the affected individuals predominantly exhibited childhood absence epilepsy and febrile convulsions. Objective To assess the role of GABRG2 in the genetic predisposition to idiopathic absence epilepsies. Design The GABRG2 gene was screened by single-strand conformation analysis for mutations. Furthermore, a population-based association study assessing a common exon 5 polymorphism (C588T) was carried out. Patients The sample was composed of 135 patients with idiopathic absence epilepsy and 154 unrelated and ethnically matched controls. Results A point mutation (IVS6 + 2T→G) leading to a splice–donor site mutation in intron 6 was found. The mutation, which is predicted to lead to a nonfunctional protein, cosegregates with the disease status in a family with childhood absence epilepsy and febrile convulsions. The association study did not find any significant differences in the allele and genotype frequencies of the common exon 5 polymorphism (C588T) between patients with idiopathic absence epilepsy and controls ( P >.35). Conclusions Our study identified a splice–donor-site mutation that was probably causing a nonfunctional GABRG2 subunit. This mutation occurred in heterozygosity in the affected members of a single nuclear family, exhibiting a phenotypic spectrum of childhood absence epilepsy and febrile convulsions. The GABRG2 gene seems to confer a rare rather than a frequent major susceptibility effect to common idiopathic absence epilepsy syndromes.
- Published
- 2002