Close association between A118G single nucleotide polymorphism and opioid, alcohol, and nicotine dependence

Correspondence: Shailendra Kapoor 2300 E Cary Street, Richmond, VA 23223, USA Email [email protected] I read with great interest the article by Cosci et al in a recent issue of your journal. The article provides for highly interesting reading and is very thought-provoking. Interestingly, the past few years have seen the emergence of extensive data that establish a close association between the A118G single nucleotide polymorphism of the OPRM1 gene and opioid, alcohol, and nicotine dependence. A higher threshold to pain has been observed in individuals with the A118G variant. Not surprisingly, Tan et al and Kapur et al have demonstrated a close association between the A118G variant and heroin dependence. Altered modulation of protein kinase A is responsible for this close association between the A118G variant of the OPRM1 gene and heroin dependency. A recent Japanese study has demonstrated that the presence of the A118G polymorphism is associated with an increased risk of addiction to alcohol. Similarly, a recent Swedish study has demonstrated that the A118G variant is associated with an 11% risk of ethanol dependency. The treatment response to naltrexone in individuals with alcohol dependency varies greatly, depending on the presence or absence of the A118G variant. In females, there is a strong association between nicotine reinforcement and the A118G haplotype. The above examples illustrate a close association between A118G polymorphism and drug dependence. Hopefully, the coming years will see increased clinical application of this close association in identifying and effectively treating individuals with this polymorphism.