However, generalization of findings from COGA may be limited due to the selective nature of this sample containing a very high proportion of severe alcoholism cases and known effects of alcohol and other co-abused substances on the human EEG that often remain unaccounted for in genetic analyses; thus this interesting finding still awaits an independent replication in a general population-based sample. It is important that linkage analysis is just an important first step to gene identification, since it only provides a probable chromosomal location of gene(s) influencing the phenotypic trait. With the advent of SNPs, there is an opportunity to test for association between the beta EEG traits and SNP located in the GABA receptor genes on chromosome 4 using the same and other datasets.
