title: Endothelin system polymorphisms in tilt test-induced vasovagal syncope.
abstract: OBJECTIVE
  As the endothelin system participates in the regulation of cardiovascular homeostasis, the aim of this study was to analyse the role of endothelin system polymorphisms in influencing tilt-induced vasovagal syncope.
  
  
  METHODS
  We evaluated 107 otherwise healthy subjects with recurrent unexplained syncope who underwent a head-up tilt test. All subjects were genotyped for the 3A/4A polymorphism of the EDN1 gene and the H323H T/C polymorphism of the EDNRA gene.
  
  
  RESULTS
  Fifty-eight patients (54%) fainted. In terms of the EDNRA polymorphism, eight subjects (8%) had the T/T genotype, 41 were heterozygous (38%) and 58 homozygous (54%) for the C allele. Sixty subjects (56%) carried homozygosis for the 3A allele of the EDN1 polymorphism and 47 were heterozygous (44%). The 4A allele was significantly more frequent in the patients who responded positively to the tilt test than in those who did not: the relative odds ratios and confidence intervals at univariate and multivariate analyses were respectively 2.37 (1.07-5.26) and 2.41 (1.05-5.49). Comparisons with a control group further supported these data. Among the tilt-positive patients, the carriers of the 4A allele were more likely to have a vasodepressive pattern than those who were homozygous for the 3A variant.
  
  
  CONCLUSIONS
  The 3A/4A polymorphism of the EDN1 gene affects susceptibility to syncope, and the 4A variant associated with increased endothelin-1 expression may promote vasodepressive hemodynamic responses during tilt testing.
authors.affiliation: Cardiology Unit, Emergency and Organ Transplantation Dept., University of Bari, Piazza Giulio Cesare 11, 70124, Bari, Italy.
authors.forename: Sandro
authors.initials: S
authors.lastname: Sorrentino
authors.forename: Cinzia
authors.initials: C
authors.lastname: Forleo
authors.forename: Massimo
authors.initials: M
authors.lastname: Iacoviello
authors.forename: Pietro
authors.initials: P
authors.lastname: Guida
authors.forename: Valentina
authors.initials: V
authors.lastname: D'Andria
authors.forename: Stefano
authors.initials: S
authors.lastname: Favale
mesh_terms: D000328:Adult; D000483:Alleles; D016232:Endothelins / Q000235:genetics*; D005260:Female; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006801:Humans; D008297:Male; D008875:Middle Aged; D020641:Polymorphism, Single Nucleotide; D019462:Syncope, Vasovagal / Q000175:diagnosis / Q000235:genetics* / Q000503:physiopathology*; D018667:Tilt-Table Test
chemical_list: D016232:Endothelins