title: Heritability of peripheral refraction in Chinese children and adolescents: the Guangzhou Twin Eye study.
abstract: OBJECTIVE
  To estimate the heritability of peripheral refraction in Chinese children and adolescents.
  
  
  METHODS
  The authors examined 72 monozygotic (MZ) twins and 48 dizygotic (DZ) twins aged 8 to 20 years from a population-based twin registry. Temporal and nasal peripheral refraction, each 40° from the visual axis, and axial refraction were measured using an autorefractor. Relative peripheral refractive error (RPRE) was defined as the peripheral refraction minus the axial refraction. Heritability was assessed by structural equation modeling after adjustment for age and sex.
  
  
  RESULTS
  The mean and SD of temporal refraction (T(40)), nasal refraction (N(40)), RPRE-T(40), RPRE-N(40), and T(40)-N(40) asymmetry were -0.27 ± 2.0 D, 0.36 ± 2.19 D, 1.18 ± 1.39 D, 1.80 ± 1.69 D, and -0.62 ± 1.58 D, respectively. The intraclass correlations for T(40) refraction, N(40) refraction, RPRE-T(40), RPRE-N(40), and T(40)-N(40) asymmetry were 0.87, 0.83, 0.65, 0.74, and 0.58 for MZ pairs and 0.49, 0.42, 0.30, 0.41, and 0.32 for DZ pairs, respectively. A model with additive genetic and unique environmental effects was the most parsimonious, with heritability values estimated as 0.84, 0.76, 0.63, 0.70, and 0.55, respectively, for the peripheral refractive parameters.
  
  
  CONCLUSIONS
  Additive genetic effects appear to explain most of the variance in peripheral refraction and relative peripheral refraction when adjusting for the effects of axial refraction.
authors.affiliation: State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, People's Republic of China.
authors.forename: Xiaohu
authors.initials: X
authors.lastname: Ding
authors.forename: Zhi
authors.initials: Z
authors.lastname: Lin
authors.forename: Qunxiao
authors.initials: Q
authors.lastname: Huang
authors.forename: Yingfeng
authors.initials: Y
authors.lastname: Zheng
authors.forename: Nathan
authors.initials: N
authors.lastname: Congdon
authors.forename: Mingguang
authors.initials: M
authors.lastname: He
mesh_terms: D000293:Adolescent; D044466:Asian People / Q000235:genetics*; D002648:Child; D002681:China; D005260:Female; D006801:Humans; D008297:Male; D019655:Quantitative Trait, Heritable; D012029:Refraction, Ocular / Q000235:genetics*; D014429:Twins, Dizygotic / Q000235:genetics*; D014430:Twins, Monozygotic / Q000235:genetics*; D055815:Young Adult