other drugs. In our analysis, we find a genome-wide significant association of NCK2 gene on chromosome 2 with opiates dependence in African-origin men at both the SNP and gene levels. NCK2 is a member of NCK family of adaptor proteins, which is associated with tyrosine-phosphorylated growth factor receptors of their cellular substrates [54]. However, to the best of our knowledge, NCK2 has not been reported to be associated with any drug addiction outcomes in humans.
