Wetherill et al. conducted a genome-wide association study examining the association between candidate genes and substance dependence and found that one SNP, rs2952621 in the uncharacterized gene LOC151121 on chromosome 2, and another SNP, rs2567261 in ARHGAP28 (Rho GTPase-activating protein 28), are associated with substance dependence [86]. This evidence concerns the gene ARHGAP28 and substance dependence.