NCK2 and opiate dependence: Overall, five genes, NCK2 (opiates dependence in black men), SH3BP5 (cocaine dependence in white men), LRP5 (opiates dependence in white men), KIAA0040 (alcohol dependence in white women), and PKNOX2 (alcohol dependence in white women), were identified by both the SNP-based and gene-based methods as meeting either of the relaxed significance levels for a specific dependence and within a gender-racial group.