title: Linkage analysis of quantitative refraction and refractive errors in the Beaver Dam Eye Study.
abstract: OBJECTIVE
  Refraction, as measured by spherical equivalent, is the need for an external lens to focus images on the retina. While genetic factors play an important role in the development of refractive errors, few susceptibility genes have been identified. However, several regions of linkage have been reported for myopia (2q, 4q, 7q, 12q, 17q, 18p, 22q, and Xq) and for quantitative refraction (1p, 3q, 4q, 7p, 8p, and 11p). To replicate previously identified linkage peaks and to identify novel loci that influence quantitative refraction and refractive errors, linkage analysis of spherical equivalent, myopia, and hyperopia in the Beaver Dam Eye Study was performed.
  
  
  METHODS
  Nonparametric, sibling-pair, genome-wide linkage analyses of refraction (spherical equivalent adjusted for age, education, and nuclear sclerosis), myopia and hyperopia in 834 sibling pairs within 486 extended pedigrees were performed.
  
  
  RESULTS
  Suggestive evidence of linkage was found for hyperopia on chromosome 3, region q26 (empiric P = 5.34 × 10(-4)), a region that had shown significant genome-wide evidence of linkage to refraction and some evidence of linkage to hyperopia. In addition, the analysis replicated previously reported genome-wide significant linkages to 22q11 of adjusted refraction and myopia (empiric P = 4.43 × 10(-3) and 1.48 × 10(-3), respectively) and to 7p15 of refraction (empiric P = 9.43 × 10(-4)). Evidence was also found of linkage to refraction on 7q36 (empiric P = 2.32 × 10(-3)), a region previously linked to high myopia.
  
  
  CONCLUSIONS
  The findings provide further evidence that genes controlling refractive errors are located on 3q26, 7p15, 7p36, and 22q11.
authors.affiliation: Department of Oncology, Johns Hopkins School of Medicine, Baltimore, Maryland, USA. aklein1@jhmi.edu
authors.forename: Alison P
authors.initials: AP
authors.lastname: Klein
authors.forename: Priya
authors.initials: P
authors.lastname: Duggal
authors.forename: Kristine E
authors.initials: KE
authors.lastname: Lee
authors.forename: Ching-Yu
authors.initials: CY
authors.lastname: Cheng
authors.forename: Ronald
authors.initials: R
authors.lastname: Klein
authors.forename: Joan E
authors.initials: JE
authors.lastname: Bailey-Wilson
authors.forename: Barbara E K
authors.initials: BE
authors.lastname: Klein
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002892:Chromosomes, Human, Pair 22; D002893:Chromosomes, Human, Pair 3; D002897:Chromosomes, Human, Pair 7; D005260:Female; D008040:Genetic Linkage; D020022:Genetic Predisposition to Disease / Q000235:genetics*; D055106:Genome-Wide Association Study; D006801:Humans; D006956:Hyperopia / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000235:genetics*