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J.R. MacKinnon, S.A. Brown, J.L. Pouslen, C.J. Hammond, L.S. Kearns, L.W. Scotter, D.A. Mackey; Genetic influence on intraocular pressure in children: the Twins Eye Study in Tasmania. . Invest. Ophthalmol. Vis. Sci. 2004;45(13):4390.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose:Raised intraocular pressure (IOP) is a major contributing factor in glaucoma. Although there are some genes associated with high–pressure glaucoma, little is known about the heritability of IOP. A classic twin study was conducted to establish the relative importance of genes and environment to IOP. Methods: Twin children from the Twins Eye Study in Tasmania had IOP measured by a Tonopen (Mentor). Zygosity was assessed by parental questionnaire and DNA analysis. Best–fit structural equation modelling was performed using the Mx program to estimate the proportion of variance explained by genetic and environmental effects. Results:Of 149 twin pairs examined in the study, IOP measurements were obtained for both twins in 42 MZ pairs (mean age+SD: 10.2+2.5 years) and 63 DZ pairs (mean age+SD: 10.4+2.5 years), ranging from 5.1 to 16.6 years of age. Mean IOP was 16.3mmHg +2.80 for the MZ pairs and 16.0+3.31 for the DZ pairs. Age was not significantly correlated with IOP (p=0.60). The correlation coefficient of mean IOP for MZ pairs was 0.65, compared to 0.37 for DZ pairs, suggesting a genetic component. Modelling results estimated a heritability of IOP of 0.70 (95% CI 0.52–0.81), with the rest of the variance explained by unique environment/measurement error (0.30, 95% CI 0.19–0.48), and no shared environment or dominant genetic effects. Conclusions: Genetic influences seem to be important in IOP in children, explaining around 70% of the variance in this group of twins.
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