Heterotrimeric guanine nucleotide binding proteins (G proteins) regulate various signals from transmembrane receptors to intracellular effectors thereby mediating cell growth, differentiation, and apoptosis. We have been publishing a series of genetic variations detected in the genomic regions corresponding to the potential drug target genes. As an addition to genetic information reported earlier, we provide here 20 novel single nucleotide polymorphisms (SNPs) in the region corresponding to a gene encoding alpha subunits of G(12) protein, GNA12, in the Japanese population: 16 in introns, two in the coding region, and two in the 3' flanking region. We also identified 12 genetic variations of other types from this locus. The collection of genetic variations reported here will serve as a useful resource for analyzing potential associations between genotypes and susceptibility to common diseases as well as efficacy and/or adverse reactions to drugs.