title: Homozygosity for the EPHX2 K55R polymorphism increases the long-term risk of ischemic stroke in men: a study in Swedes.
abstract: OBJECTIVE
  The soluble epoxide hydrolase (gene name EPHX2) is responsible for metabolism of 8,9 11,12 and 14,15-epoxyeicosatrienoic acids, vasodilator and anti-inflammatory substances. There are several functional polymorphisms in the EPHX2 gene: two of them, the K55R and R287Q, showing an altered metabolic activity in vitro, were associated with coronary heart disease and ischemic stroke in previous studies. The aim of this study was to evaluate the effect of four polymorphisms in the EPHX2 gene on blood pressure levels, hypertension prevalence, and risk of incident cardiovascular events in a large sample of middle-aged Swedes.
  
  
  METHODS
  The incidence of cardiovascular events (coronary events, n = 274; ischemic stroke, n = 197) was monitored over 10 years of follow-up.
  
  
  RESULTS
  In the whole population, all polymorphisms had no effect on the studied parameters but a positive interaction between male sex and three SNPs including the K55R was evident: male, but not female, EPHX2 R55R homozygotes had significantly higher crude and adjusted systolic blood pressure and higher hypertension prevalence with respect to K-carriers. Kaplan-Meier curves showed higher incidence of ischemic strokes in male R55R homozygotes with respect to K-carriers (P = 0.015 by log-rank test). After adjustment for major cardiovascular risk factors, the hazard ratio for incident ischemic stroke in male R55R homozygotes remained significantly higher (hazard ratio: 4.8; 95% confidence interval: 1.2-19.9).
  
  
  CONCLUSIONS
  The functional K55R polymorphism of the EPHX2 gene confers a higher risk of hypertension prevalence and increases the risk of incident ischemic stroke in male homozygotes. Additional studies are needed to confirm these data and to elucidate the interaction between sex and the EPHX2 K55R polymorphism.
authors.affiliation: Department of Clinical Sciences, Lund University, University Hospital of Malmö, Sweden. cristiano.fava@med.lu.se
authors.forename: Cristiano
authors.initials: C
authors.lastname: Fava
authors.forename: Martina
authors.initials: M
authors.lastname: Montagnana
authors.forename: Elisa
authors.initials: E
authors.lastname: Danese
authors.forename: Peter
authors.initials: P
authors.lastname: Almgren
authors.forename: Bo
authors.initials: B
authors.lastname: Hedblad
authors.forename: Gunnar
authors.initials: G
authors.lastname: Engström
authors.forename: Göran
authors.initials: G
authors.lastname: Berglund
authors.forename: Pietro
authors.initials: P
authors.lastname: Minuz
authors.forename: Olle
authors.initials: O
authors.lastname: Melander
mesh_terms: D019943:Amino Acid Substitution / Q000235:genetics; D001794:Blood Pressure / Q000502:physiology; D003710:Demography; D023381:Endpoint Determination; D004851:Epoxide Hydrolases / Q000235:genetics*; D005260:Female; D020022:Genetic Predisposition to Disease; D006720:Homozygote; D006801:Humans; D006973:Hypertension / Q000150:complications / Q000235:genetics / Q000503:physiopathology; D015994:Incidence; D007511:Ischemia / Q000150:complications* / Q000453:epidemiology / Q000235:genetics / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*; D012727:Sex Characteristics; D020521:Stroke / Q000453:epidemiology / Q000209:etiology* / Q000235:genetics* / Q000503:physiopathology; D013548:Sweden / Q000453:epidemiology
chemical_list: D004851:Epoxide Hydrolases; C506428:EPHX2 protein, human