known risk factor. Based on a joint-analysis, SNPs within ADAMTS7 and MORF4L1 were recently listed as candidate signals for smoking behaviour independent of those yielded by the known loci rs16969968 or rs588765 in CHRNA5 31. Regarding the two significant associations on chromosome 1 (i.e., SHISA4 and IPO9 genes, P=1.52E-06 and 5.45E-06, respectively), we note that neither of these have been previously associated with any addiction behaviour.
