In African Americans, the variant with the smallest P value for association of allele frequency with heroin addiction was variant rs950302 (point-wise P = 0.0079, Table 3). This variant is in the second intron of the dual specificity phosphatase 27 (putative) gene DUSP27. This gene encodes a recently identified member of the cytosolic dual specificity phosphatase family, which may be involved in energy metabolism (Friedberg et al., 2007).
