Despite the high heritability estimates provided by twin and family studies (49–85%11,12), there have been relatively few genetic studies of beta EEG, and to date, only one finding has replicated. An early analysis found linkage between beta EEG and a region of chromosome 424 harboring variants in the gene that encodes GABA α2 (GABRA2).25 More recently, a study of 586 individuals of European ancestry with Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) Alcohol Dependence (AD) and 603 controls26 replicated the association between beta activity and GABRA2 single-nucleotide polymorphisms (SNPs). To date, only two genome-wide association studies (GWASs) of beta EEG have been conducted.12,27 In a study of 322 Native-American individuals, there were no genome-wide significant associations reported for beta EEG.27 A recent GWAS of monopolar beta EEG in 4026 European ancestry adolescent twins and their parents12 did not report any genome-wide significant variants but replicated the previous associations observed with GABRA2.
