In Caucasians, variant rs10494334, located on chromosome 1, had the smallest P values for association with vulnerability to develop heroin addiction, which was significant after correcting for multiple testing. This variant has no annotated genes within 100,000 nucleotides. However, there is a region of approximately 50 nucleotides, located 600 nucleotides from this variant, that is highly conserved. This region is rich in predicted transcription factor binding sites and could be a region controlling expression of many genes (Morley et al., 2004).
