Chidambaran V, et al. - Given the emerging evidence inferring the estimated heritability of 45% for chronic pain and that individual susceptibility to Chronic postsurgical pain (CPSP) is partially related to genetic factors, researchers performed this systematic review of studies in humans that have investigated genetic factors associated with CPSP. A meta-analysis was conducted in addition to determine a single effect size for evaluable genetic associations with CPSP. They performed a comprehensive literature search incorporating a review of 21 full-text articles evaluating variants of 69 genes for correlation with CPSP. Systematic literature review infers that variants of 26 genes involved in different nociceptive pathways had genetic associations with chronic post-surgical pain (CPSP). The meta-analysis included 6 variants of 5 genes (COMT, OPRM1, GCH1, KCNS1, TNFA). Marginal increase in the risk of CPSP was found in relation to the presence of G allele at rs734784 (A>G) of KCNS1. Study heterogeneity in surgical populations, methodology and outcomes limited the meta-analysis.