Abstract. One of the typical manifestations of hemorrhagic fever with renal syndrome (HFRS) is a damage to the cardiovascular system. The most promising direction of studying the causes of cardiac complications in HFRS should be considered the genetic patient characteristics, particularly taking into account the disease pathogenesis, study of polymorphism of the genes in the blood coagulation system and the folate cycle. The aim of the study was to find out an effect of polymorphism of the blood coagulation system and folate cycle genes on heart damage in hemorrhagic fever with renal syndrome. A case-control study was conducted by enrolling 19 patients in the 2019 summer-autumn period at the Republican clinical infectious disease hospital in the city of Izhevsk. The study of polymorphism of the blood coagulation system and folate cycle genes was performed by using a set of reagents "Realbest-Genetics Hemostasis (12)" on the "CFX96" amplifier (Bio-Rad, USA). DNA was extracted from peripheral blood leukocytes with reagents "Realbest Extraction 100". Transthoracic echocardiography was performed on a Vivid 7 Dimension ultrasound scanner (GE Healthcare, USA) with a matrix sector sensor M4S with a phased array at scanning frequency of 1.5-4.3 MHz. The group parameters were calculated and depicted as median and interquartile range (ME [Q25;Q75]). Comparison of such parameters was carried out by using the Mann-Whitney criterion. Comparison of the frequency distribution for genotypes and alleles in the study groups was carried out using the criterion χ2. The association of alleles/genotypes with a predisposition to detectable changes was assessed by the risk ratio (OR) additionally calculating 95% confidence interval (CI) . The p≤0.05 was considered as statistically significant. During the study, 7 patients were found to have floating echoes on the aortic valve in the outlet of the left ventricle - signs of thrombotic endocarditis. In the group of patients with signs of thrombotic endocarditis, there was revealed a higher frequency of the allele A for the F7:10976 G/A gene compared to patients lacking signs of thrombotic endocarditis (p=0.0357). All study patients had a normal left ventricular ejection fraction (more than 50%), but during the speckle-tracking study assessing the index of averaged peak longitudinal contractility (GLPS AVG), 11 patients with impaired myocardial contractility were identified. In patients with decreased GLPS AVG, the genograde G/G of the FGB:-455 G/A gene was detected more often compared to patients with preserved myocardial contractility (p=0.0397). In 8 patients, signs of grade 1 diastolic left ventricular dysfunction were revealed, the prognostic importance of the gene polymorphism related to the blood coagulation system and folate cycle in developing this complication has not been determined.
