title: Hemodynamic parameters and heart rate variability during a tilt test in relation to gene polymorphism of renin-angiotensin and serotonin system.
abstract: OBJECTIVE
  The aim of the study was to evaluate the renin-angiotensin system and serotonin transporter gene polymorphisms in relation to hemodynamic parameters and heart rate variability during a head-up tilt test (HUT) in patients with vasovagal syncope.
  
  
  METHODS
  DNA was collected from 191 patients (mean age 44+/-18 years, 61 men, 130 women). The following gene polymorphisms were determined in genomic DNA: angiotensin-converting enzyme insertion/deletion polymorphism (I/D ACE), angiotensinogen gene polymorphism (M 235), angiotensin II receptor type 1 (ATR1) polymorphism (A 11666C), and polymorphism of serotonin transporter gene (5HTTLPR).Heart rate variability during HUT was assessed in 5-minute intervals by low frequency, high frequency, standard deviation of the normal-to-normal (SDNN), and root mean square successive difference parameters.
  
  
  RESULTS
  AA genotype of A 1166C polymorphism was associated with lower minimal systolic blood pressure (SBP) and diastolic blood pressure (DBP) during HUT compared with other genotypes (minimal SBP: AA 59.6+/-21,8, AC 79.9+/-22.7, CC 65.4+/-22.7 mmHg, P=0.007), (minimal DBP: AA 36.4+/-22.7, AC 52.3+/-22.9, CC 45.4+/-19.5 mmHg, P=0.007).AA genotype was also associated with higher SDNN compared to other genotypes in the early phase of HUT (SDNN in 5 minutes of tilt: AA 59.7+/-24.6, AC 50.6+/-20.6, CC 46.0+/-13.2, P=0.01) and at syncope occurrence (SDNN: AA 71.0+/-20.9, AC 58.2+/-17.9, CC 58+/-10, P=0.04)
  
  
  CONCLUSIONS
  AA genotype of A 1166C polymorphism in the ATR1 gene may be associated with hypotension and decline in sympathetic tone during HUT. Its role in genetic predisposition to vasovagal syncope cannot be excluded.
authors.affiliation: Clinic of Internal Medicine III, Medical Faculty, P.J. Safarik University, Kosice, Slovakia. pmitro@lf.upjs.sk
authors.forename: Peter
authors.initials: P
authors.lastname: Mitro
authors.forename: Klaudia
authors.initials: K
authors.lastname: Mudráková
authors.forename: Helena
authors.initials: H
authors.lastname: Micková
authors.forename: Ján
authors.initials: J
authors.lastname: Dudás
authors.forename: Peter
authors.initials: P
authors.lastname: Kirsch
authors.forename: Gabriel
authors.initials: G
authors.lastname: Valocik
mesh_terms: D000328:Adult; D000085962:Angiotensin-Converting Enzyme 2; D000808:Angiotensinogen / Q000235:genetics*; D001783:Blood Flow Velocity; D001794:Blood Pressure; D005260:Female; D020022:Genetic Predisposition to Disease / Q000235:genetics; D006339:Heart Rate / Q000235:genetics*; D006801:Humans; D008297:Male; D007703:Peptidyl-Dipeptidase A / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D044139:Receptor, Angiotensin, Type 2 / Q000235:genetics*; D012084:Renin-Angiotensin System / Q000235:genetics; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D050486:Serotonin Plasma Membrane Transport Proteins / Q000235:genetics*; D019462:Syncope, Vasovagal / Q000503:physiopathology*; D018667:Tilt-Table Test
chemical_list: D044139:Receptor, Angiotensin, Type 2; D050486:Serotonin Plasma Membrane Transport Proteins; D000808:Angiotensinogen; D007703:Peptidyl-Dipeptidase A; C000705307:ACE2 protein, human; D000085962:Angiotensin-Converting Enzyme 2