title: Association analysis of GABAAbeta2 and gamma2 gene polymorphisms with event-related prefrontal activity in man.
abstract: Gamma-aminobutyric acid (GABA)A-receptors play a crucial role in the generation of electroencephalogram (EEG) oscillations and evoked potentials (ERPs). The present association study was designed to test whether EEG and ERPs are modulated by genetic variations of the human GABAA beta2 (GABRB2) and gamma2 (GABRG2) genes on chromosome 5q33. The genotypes of two nucleotide substitution polymorphisms of the GABRB2 and GABRG2 genes were assessed in 95 psychiatrically healthy subjects of German descent. Neurophysiological phenotyping was performed with four factorized EEG/ERP parameters: EEG activation, anterior and posterior EEG synchronization, and event-related activity (N100/ P200-complex). No genotypic association was found for the GABRB2 nucleotide exchange polymorphism with any electrophysiological parameter. A significant association was found between the genotype of the intronic GABRG2 G-->A nucleotide exchange and the event-related N100/P200 (ANOVA: F=3.81; df=2; P=0.026). A comparison of homozygous subjects carrying either the G/G or A/A genotype of the GABRG2 polymorphism consistently revealed an even stronger difference in the effect-size (ANOVA: F=11.13; df=1; P=0.002). Post hoc analysis of this association with current density analysis in three-dimensional neuroanatomic Talairach space-time showed a reduction in the event-related signal power after 120 ms in the right dorsolateral prefrontal cortex. Taking into account the risk of false-positive association findings attributable to multiple testing, our results encourage further replication studies to examine the phenotype-genotype relationship of GABRG2 gene variants and event-related prefrontal activity.
authors.affiliation: Department of Psychiatry, University Hospital Benjamin Franklin, Free University of Berlin, Germany. wintereg@intra.nimh.nih.gov
authors.forename: G
authors.initials: G
authors.lastname: Winterer
authors.forename: M
authors.initials: M
authors.lastname: Smolka
authors.forename: J
authors.initials: J
authors.lastname: Samochowiec
authors.forename: C
authors.initials: C
authors.lastname: Mulert
authors.forename: M
authors.initials: M
authors.lastname: Ziller
authors.forename: R
authors.initials: R
authors.lastname: Mahlberg
authors.forename: Y
authors.initials: Y
authors.lastname: Wuebben
authors.forename: J
authors.initials: J
authors.lastname: Gallinat
authors.forename: H
authors.initials: H
authors.lastname: Rommelspacher
authors.forename: W M
authors.initials: WM
authors.lastname: Herrman
authors.forename: T
authors.initials: T
authors.lastname: Sander
mesh_terms: D000328:Adult; D001483:Base Sequence; D002874:Chromosome Mapping; D002895:Chromosomes, Human, Pair 5; D017931:DNA Primers; D004569:Electroencephalography; D004574:Electromagnetic Fields; D005071:Evoked Potentials; D005260:Female; D014644:Genetic Variation; D005838:Genotype; D005858:Germany; D006801:Humans; D008297:Male; D010641:Phenotype; D011110:Polymorphism, Genetic; D012150:Polymorphism, Restriction Fragment Length; D017397:Prefrontal Cortex / Q000502:physiology*; D011963:Receptors, GABA-A / Q000737:chemistry / Q000235:genetics* / Q000502:physiology*; D012016:Reference Values; D044465:White People
chemical_list: D017931:DNA Primers; D011963:Receptors, GABA-A