While meta-analyses are pending for other substances, individual GWAS have yielded promising leads for cocaine and opioids. A recent GWAS of cocaine dependence identified rs2629540 in FAM53B [85]. The same group of investigators has also recently reported genomewide significant association signals for genes in potassium signalling pathways for opioid dependence [86]. In contrast, results for cannabis use and dependence have been less promising [87, 88]. Despite the lack of statistically significant findings, there is growing evidence that common GWAS variation explains 24-38% of the variation in current smoking [89] and alcoholism [90].
