As yet, no GABRA2 functional variant has been detected to explain the yin yang haplotype (or tag SNP) associations with alcoholism-related phenotypes. HapMap data and other studies [52] reveal moderate long distance linkage disequilibrium across GABRA2 and the closely adjacent gene GABRG1 raising the possibility that the functional locus is in GABRG1. The results of several studies suggest that there are likely to be independent, complex contributions to alcoholism vulnerability from both linked genes [52–54].
