Objective: To systematically evaluate variations in single-nucleotide polymorphisms within 13 candidate pain genes in patients differing in phenotype characteristics based on a composite measure of pain sensitivity.
Methods: In a case-control study, 149 patients scheduled for laparoscopic cholecystectomy were individually categorized according to preoperative pain sensitivity and postoperative pain intensity. Cases (pain group) reported cannulation-induced pain intensity higher than 2.0, together with postoperative pain intensity of 7.0 or higher (visual analog scale [VAS] units), and controls (low-pain group) reported cannulation-induced pain intensity of 2.0 or lower, together with postoperative pain intensity lower than 4.0 (VAS units). Genotyping of exomes was performed in 32 case and 25 control patients compared with respect to variations within 13 candidate pain genes.
Results: There were no statistically significant differences in single nucleotide polymorphisms (SNPs) within the candidate genes between the case and control groups, but minor allele SNPs in the ABCB1 and COMT genes were more common in patients with higher levels of pain sensitivity and intensity.
Conclusion: In this candidate gene study, based on a composite measure of pain sensitivity, no variations reached statistical significance after correction for multiple testing, most likely due to the large number of markers analyzed and few patients. Nevertheless, the results suggest a possible genetic contribution of single-nucleotide polymorphisms within the ABCB1 and COMT genes in individuals with higher levels of pain sensitivity.