SNPs rs4141854, rs9394515, and rs4711553 on Chromosome 6, which have statistically significant POE on alcohol dependence, were located in the same gene, BTBD9. The BTBD9 gene is located on the short arm of Chromosome 6 and is highly expressed throughout the human brain (Freeman et al., 2012), and its mutation has been shown to be associated with restless legs syndrome and Tourette’s syndrome (Rivière et al., 2009; Schormair et al., 2017; Lyu et al., 2019). Here, BTBD9 is linked to Tourette syndrome.