USF1 and drug dependence: Bioinformatic analysis showed that CpG cg17108064 [802 bp from the transcription start site (TSS) of CHRNA5] is located in a potential core binding site (CCACGT) for the upstream stimulatory factor (USF, a helix-loop-helix transcription factor), consistent with the interpretation that altered methylation of cg17108064 may affect the transcription of CHRNA5 and lead to increased risk for alcohol or drug dependence.