Genetic susceptibility to postherniotomy pain. The influence of polymorphisms in the Mu opioid receptor, TNF-α, GRIK3, GCH1, BDNF and CACNA2D2 genes

Background and aimsDespite improvements in surgical technique, 5%-8% of patients undergoing herniorrhaphy still suffer from clinically relevant persistent postherniotomy pain. This is a problem at both individual and society levels. The aim of this study was to determine whether or not a single nucleotide polymorphism in a specific gene contributes to the development of persistent pain after surgery.MethodsOne hundred individuals with persistent postherniotomy pain, along with 100 without pain matched for age, gender and type of surgery were identified in a previous cohort study on patients operated for groin hernia. All patients underwent a thorough sensory examination and blood samples were collected. DNA was extracted and analysed for single nucleotide polymorphism in the Mu opioid receptor, TNF-α, GRIK3, GCH1, BDNF and CACNA2D2 genes.ResultsPatients with neuropathic pain were found to have a homozygous single nucleotide polymorph in the TNF-α gene significantly more often than pain-free patients (P =0.036, one-tailed test). ConclusionsSNP in the TNF-α gene has a significant impact on the risk for developing PPSP.ImplicationsThe result suggests the involvement of genetic variance in the development of pain and this requires further investigation.