Introduction: The prediction of postoperative abdominal complications is a continuing concern in the cardiac surgery. Identifying genetic predictors will allow a better understanding of the pathophysiological mechanisms underlying postoperative disorders and their prevention.Objective: To identify genetic predictors of abdominal complications after heart surgery.Methods: A prospective study was carried out at the Federal Center for Cardiovascular Surgery (Chelyabinsk) involving 72 patients with abdominal complications and 102 controls without such complications. The distribution of genotypes was assessed for adherence to the Hardy-Weinberg distribution using the exact method according to the SNP-HWE algorithm in the PLINK package (version 1.9). To identify marker genes associated with the risk of abdominal complications, 6 models were evaluated for each polymorphic gene: allelic, codominant, dominant, recessive, overdominant, and log-additive. To analyze the SNPs of the IL6 (rs1800795), TNF (rs1800629), and SERPINE1 (rs1799768) genes, real-time polymerase chain reaction (PCR) was performed on a Rotor-Gene 6000 detecting cycler (Corbett Research Pty Ltd., Mortlake, Australia) using primers and probes manufactured by Syntol CJSC (Moscow, Russia) according to the manufacturer's instructions. To analyze the SNPs of the IL1B (rs1143634), CXCL8 (rs4073), IL10 (rs1800872), APOE (rs429358), FABP2 (rs1799883), NOS3 (rs1799983), VEGFA (rs699947) genes, real-time PCR was performed on a DTprime 4 analyzer (DNA-Technology, Moscow, Russia) using primers and probes manufactured by TestGene LLC (Ulyanovsk, Russia) according to the manufacturer's instructions. The determination of the SNP of the TLR3 gene (rs3775291) relied on real-time PCR according to melting curves using TestGene LLC reagent kits on a DTprime 4 device.Results: Two genes, IL1B rs1143634 and FABP2 rs1799883, were found to be associated with the risk of abdominal complications. Following the adjustment for multiple comparisons, only FABP2 rs1799883 remained statistically significant. The rs1799883 polymorphism of the FABP2 gene can be considered a predictor of the risk of abdominal complications and can be evaluated within the codominant and dominant models, which exhibit similar p-values (0.003 and 0.002, respectively). Overall, the analysis of the obtained data suggests that the risk of abdominal complications is associated with the presence of the mutant allele C in the genome, likely due to its dominance. Specifically, in the dominant model, the odds ratio was 3.53 (95% CI 1.62 to 7.70).Conclusion: The most significant markers of the risk of abdominal complications were the IL1B (rs1143634) and FABP2 (rs1799883) genes, of which FABP2 (rs1799883) remained statistically significant after adjusting for multiple comparisons. Its polymorphism as a predictor of abdominal complications can be evaluated within the codominant and dominant models. Received 13 June 2023. Revised 28 November 2023. Accepted 29 November 2023. Funding: The study was supported by the Russian Science Foundation, project No. 22-25-20016, https://rscf.ru/project/22-25-20016/ Conflict of interest: The authors declare no conflict of interest. Contribution of the authorsConception and study design: O.S. Abramovskikh, A.A. Fokin, D.V. BelovData collection and analysis: Yu.V. LoginovaStatistical analysis: M.A. ZotovaDrafting the article: D.V. BelovCritical revision of the article: Yu.V. LoginovaFinal approval of the version to be published: D.V. Belov, O.S. Abramovskikh, M.A. Zotova, Yu.V. Loginova, A.A. Fokin