title: Heritability of early repolarization: a population-based study.
abstract: BACKGROUND
  Early repolarization (ER), defined by J-point elevation in 12-lead ECG, was recently associated with increased risk for idiopathic ventricular fibrillation and cardiovascular mortality. The determinants of ER are unknown. We investigated its heritability in a large, family-based cohort.
  
  
  RESULTS
  The study sample comprised 1877 individuals from 505 white nuclear families representative of the British general population. Standard 12-lead ECGs were evaluated for the presence of ER, defined as J-point elevation of ≥0.1 mV in at least 2 adjacent inferior (II, III, and aVF) or anterolateral (I, aVL, and V(4) through V(6)) leads. Narrow sense heritability estimates were computed adjusting for age, age(2), and sex. The prevalence of ER was 7.7% (n=145) in the whole cohort, 5.9% (n=56) in parents, and 9.6% (n=89) in offspring. Heritability estimate for the presence of ER was calculated at h(2)=0.49 (standard error=0.14; P=2.7*10(-4)) and was higher when restricted to its presence in inferior leads (h(2)=0.61, standard error=0.18, P=4.3*10(-4)) or for the notching ER morphology (h(2)=0.81, standard error=0.19, P=2.4*10(-5)). Individuals with at least 1 affected parent had a 2.5-fold increased risk for presenting with ER on ECG (odds ratio, 2.54; 95% confidence interval, 1.33 to 4.84; P=0.005). Familial transmission was more frequent when the mother was affected (odds ratio, 3.84; 95% confidence interval, 1.41 to 10.43; P=0.008) than when the father was affected (odds ratio, 1.82; 95% confidence interval, 0.82 to 4.03; P=0.141), although this difference was not statistically significant (P=0.18).
  
  
  CONCLUSIONS
  ER is a heritable phenotype. Offspring of ER-positive parents have a 2.5-fold increased risk of presenting with ER on their ECG.
authors.affiliation: Clinic and Policlinic for Internal Medicine II, University Hospital Regensburg, Germany.
authors.forename: Wibke
authors.initials: W
authors.lastname: Reinhard
authors.forename: Bernhard M
authors.initials: BM
authors.lastname: Kaess
authors.forename: Radoslaw
authors.initials: R
authors.lastname: Debiec
authors.forename: Christopher P
authors.initials: CP
authors.lastname: Nelson
authors.forename: Klaus
authors.initials: K
authors.lastname: Stark
authors.forename: Martin D
authors.initials: MD
authors.lastname: Tobin
authors.forename: Peter W
authors.initials: PW
authors.lastname: Macfarlane
authors.forename: Maciej
authors.initials: M
authors.lastname: Tomaszewski
authors.forename: Nilesh J
authors.initials: NJ
authors.lastname: Samani
authors.forename: Christian
authors.initials: C
authors.lastname: Hengstenberg
mesh_terms: D000293:Adolescent; D000328:Adult; D015331:Cohort Studies; D004562:Electrocardiography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D010641:Phenotype; D011153:Population; D011159:Population Surveillance / Q000379:methods; D012306:Risk; D014693:Ventricular Fibrillation / Q000503:physiopathology