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H.G. Lemij, L.M. E. van Koolwijk, L.M. Pardo Cortes, C.C. W. Klaver, D.D. G. Despriet, B.A. Oostra, C.M. van Duijn; Heritability and Determinants of Intraocular Pressure in an Isolated Population in the Netherlands . Invest. Ophthalmol. Vis. Sci. 2006;47(13):190.
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© ARVO (1962-2015); The Authors (2016-present)
To investigate the heritability of intraocular pressure (IOP) and the components which determine the total phenotypic variance of this trait within an isolated population in the Netherlands.
We assessed ophthalmologic and non–ophthalmologic clinical parameters among 1977 subjects from the Erasmus Rucphen Family (ERF) study, an extended pedigree study in a Dutch genetic isolate. IOP was measured bilaterally with Goldmann appplanation tonometry. Risk associations were analyzed by univariate and multivariate regression analyses, and a final model for heritability estimation was determined. A variance component maximum likelihood approach (SOLAR 2.1.2. software package) was used to divide the total phenotypic variance of IOP into additive genetic and environmental elements. We estimated heritability as the proportion of phenotypic variance explained by additive genetic effects after adjustment for covariates.
The mean age was 48.1 years (range 18.0–86.1) and the mean IOP was 14.9 mmHg (range 8–30). 81.1% of the subjects were inbred, i.e. had consanguineous parents. Inbreeding significantly effected IOP (ß= 0.112, p–value <0.001). Age, spherical equivalent, length of eye axis, mean diastolic pressure, fasting glucose level, and the ratio total cholesterol / high density lipoprotein cholesterol were also significantly associated with IOP. The proportion of the total phenotypic variance of IOP explained by these covariates was 0.055. The heritability estimate for IOP explaining the remaining variance was 0.40 (p value < 0.001), indicating that additive genetic effects account for 40% of the residual variance, and 38% of the total variance of IOP.
Additive genetic effects accounted for 38% of the total phenotypic variance of IOP, which indicates that IOP is a strongly inherited risk factor for glaucoma.
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