was 44,000 nucleotides upstream of the neural cell adhesion molecule 1 NCAM1 (point-wise P = 0.0003) (Table 5A). In the African American group, the variant with the smallest P value was in the gene encoding the cAMP-specific phosphodiesterase 4B PDE4B (point-wise P = 0.0079) and the variant with the second smallest P value was in the N-methyl D-aspartate 2A ionotropic glutamate receptor gene GRIN2A (point-wise P = 0.0079) (Table 5B). None of these variants were found to have experiment-wise significant association with heroin addiction.
