title: Identification of a candidate gene for astigmatism.
abstract: OBJECTIVE
  Astigmatism is a common refractive error that reduces vision, where the curvature and refractive power of the cornea in one meridian are less than those of the perpendicular axis. It is a complex trait likely to be influenced by both genetic and environmental factors. Twin studies of astigmatism have found approximately 60% of phenotypic variance is explained by genetic factors. This study aimed to identify susceptibility loci for astigmatism.
  
  
  METHODS
  We performed a meta-analysis of seven genome-wide association studies that included 22,100 individuals of European descent, where astigmatism was defined as the number of diopters of cylinder prescription, using fixed effect inverse variance-weighted methods.
  
  
  RESULTS
  A susceptibility locus was identified with lead single nucleotide polymorphism rs3771395 on chromosome 2p13.3 (meta-analysis, P = 1.97 × 10(-7)) in the VAX2 gene. VAX2 plays an important role in the development of the dorsoventral axis of the eye. Animal studies have shown a gradient in astigmatism along the vertical plane, with corresponding changes in refraction, particularly in the ventral field.
  
  
  CONCLUSIONS
  This finding advances the understanding of refractive error, and provides new potential pathways to be evaluated with regard to the development of astigmatism.
authors: Department of Twin Research and Genetic Epidemiology, King's College London, St. Thomas' Hospital, London, United Kingdom.
authors: Margarida C
authors: MC
authors: Lopes
authors: Pirro G
authors: PG
authors: Hysi
authors: Virginie J M
authors: VJ
authors: Verhoeven
authors: Stuart
authors: S
authors: Macgregor
authors: Alex W
authors: AW
authors: Hewitt
authors: Grant W
authors: GW
authors: Montgomery
authors: Phillippa
authors: P
authors: Cumberland
authors: Johannes R
authors: JR
authors: Vingerling
authors: Terri L
authors: TL
authors: Young
authors: Cornelia M
authors: CM
authors: van Duijn
authors: Ben
authors: B
authors: Oostra
authors: Andre G
authors: AG
authors: Uitterlinden
authors: Jugnoo S
authors: JS
authors: Rahi
authors: David A
authors: DA
authors: Mackey
authors: Caroline C W
authors: CC
authors: Klaver
authors: Toby
authors: T
authors: Andrew
authors: Christopher J
authors: CJ
authors: Hammond
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001251:Astigmatism / Q000235:genetics*; D001315:Australia; D002889:Chromosomes, Human, Pair 2; D004777:Environment; D005260:Female; D020022:Genetic Predisposition to Disease / Q000235:genetics; D055106:Genome-Wide Association Study; D005838:Genotype; D018398:Homeodomain Proteins / Q000235:genetics*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009426:Netherlands; D010641:Phenotype; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*; D012042:Registries / Q000706:statistics & numerical data; D006113:United Kingdom; D055815:Young Adult
chemical_list: D018398:Homeodomain Proteins; C492362:VAX2 protein, human