title: Heritability of anterior chamber depth as an intermediate phenotype of angle-closure in Chinese: the Guangzhou Twin Eye Study.
abstract: OBJECTIVE
  To assess the heritability of anterior chamber depth (ACD) and relative anterior chamber depth (ACD/axial length, rACD) in Chinese in a classic twin study.
  
  
  METHODS
  Twins aged 7 to 15 years living in two local districts were recruited from the Guangzhou Twin Registry. Anterior chamber depth and axial length were measured by partial coherence laser interferometry. Zygosity in all same-sex twin pairs was confirmed by genotyping with 16 polymorphic markers. The phenotypes of the right eyes were used in analysis. Heritability was assessed by structural variance component genetic modeling.
  
  
  RESULTS
  In total, 1126 twin participants were available for analysis, including 357 monozygotic (MZ) and 206 dizygotic (DZ) twin pairs. ACD increased with age (0.036 mm per year, P < 0.001) and 0.09 mm shallower in the girls than in the boys (P < 0.001). Age- and sex-adjusted intraclass correlation coefficients (ICCs) for ACD were 0.92 for the MZ and 0.50 for the DZ twins; those for rACD were 0.89 for the MZ and 0.52 for the DZ twins. The best-fitting model yielded 90.1% (95% CI: 88.2%-91.7%) of additive genetic and 9.9% (95% CI: 8.3%-11.8%) of unique environmental effects for ACD and 89.2% (95% CI: 87.1%-90.9%) of additive genetic and 10.8% (95% CI: 9.1%-12.9%) of unique environmental effects for rACD.
  
  
  CONCLUSIONS
  Additive genetic effects appear to be the major contributor to the variation of ACD and rACD in Chinese population. High heritability remained even when the data were corrected for the influence of myopia.
authors.affiliation: State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China. mingguang_he@yahoo.com
authors.forename: Mingguang
authors.initials: M
authors.lastname: He
authors.forename: Dandan
authors.initials: D
authors.lastname: Wang
authors.forename: Yingfeng
authors.initials: Y
authors.lastname: Zheng
authors.forename: Jian
authors.initials: J
authors.lastname: Zhang
authors.forename: Qiuxia
authors.initials: Q
authors.lastname: Yin
authors.forename: Wenyong
authors.initials: W
authors.lastname: Huang
authors.forename: David A
authors.initials: DA
authors.lastname: Mackey
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Foster
mesh_terms: D000293:Adolescent; D000867:Anterior Chamber / Q000473:pathology*; D000886:Anthropometry; D044466:Asian People / Q000235:genetics*; D002648:Child; D002681:China / Q000453:epidemiology; D004200:Diseases in Twins / Q000235:genetics*; D005260:Female; D005838:Genotype; D015812:Glaucoma, Angle-Closure / Q000235:genetics*; D006801:Humans; D040582:Inheritance Patterns; D007368:Interferometry / Q000379:methods; D007834:Lasers; D008297:Male; D008957:Models, Genetic; D010641:Phenotype; D012042:Registries; D014429:Twins, Dizygotic / Q000235:genetics*; D014430:Twins, Monozygotic / Q000235:genetics*