title: Heritability and familial aggregation of refractive error in the Old Order Amish.
abstract: OBJECTIVE
  To determine the heritability of refractive error and familial aggregation of myopia and hyperopia in an elderly Old Order Amish (OOA) population.
  
  
  METHODS
  Nine hundred sixty-seven siblings (mean age, 64.2 years) in 269 families were recruited for the Amish Eye Study in the Lancaster County area of Pennsylvania. Refractive error was determined by noncycloplegic manifest refraction. Heritability of refractive error was estimated with multivariate linear regression as twice the residual sibling-sibling correlation after adjustment for age and gender. Logistic regression models were used to estimate the sibling recurrence odds ratio (OR(s)). Myopia and hyperopia were defined with five different thresholds.
  
  
  RESULTS
  The age- and gender-adjusted heritability of refractive error was 70% (95% CI: 48%-92%) in the OOA. Age and gender-adjusted OR(s) and sibling recurrence risk (lambda(s)), with different thresholds defining myopia ranged from 3.03 (95% CI: 1.58-5.80) to 7.02 (95% CI: 3.41-14.46) and from 2.36 (95% CI: 1.65-3.19) to 5.61 (95% CI: 3.06-9.34). Age and gender-adjusted OR(s) and lambda(s) for different thresholds of hyperopia ranged from 2.31 (95% CI: 1.56-3.42) to 2.94 (95% CI: 2.04-4.22) and from 1.33 (95% CI: 1.22-1.43) to 1.85 (95% CI: 1.18-2.78), respectively. Women were significantly more likely than men to have hyperopia. There was no significant gender difference in the risk of myopia.
  
  
  CONCLUSIONS
  In the OOA, refractive error is highly heritable. Hyperopia and myopia aggregate strongly in OOA families.
authors.affiliation: Department of Ophthalmology, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
authors.forename: Jon A
authors.initials: JA
authors.lastname: Peet
authors.forename: Mary-Frances
authors.initials: MF
authors.lastname: Cotch
authors.forename: Robert
authors.initials: R
authors.lastname: Wojciechowski
authors.forename: Joan E
authors.initials: JE
authors.lastname: Bailey-Wilson
authors.forename: Dwight
authors.initials: D
authors.lastname: Stambolian
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D005006:Ethnicity / Q000235:genetics*; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D006956:Hyperopia / Q000235:genetics*; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000235:genetics*; D016017:Odds Ratio; D010414:Pennsylvania; D019655:Quantitative Trait, Heritable; D044465:White People / Q000235:genetics