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Robert Wojciechowski, Pradeep Y. Ramulu, Srinivasan Kavitha, Periasamy Sundaresan, Ramamoothy Jayanthi, David S. Friedman, Rengaraj Venkatesh; Heritability Of Ocular Biometry Parameters Using Structural Equation Modeling In A Study Of Angle-closure Glaucoma. Invest. Ophthalmol. Vis. Sci. 2012;53(14):5644.
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© ARVO (1962-2015); The Authors (2016-present)
To estimate the heritabilities of components of axial length in a sibship study of primary angle-closure glaucoma.
Probands with primary angle closure suspicion, primary angle closure or primary angle closure glaucoma, and open angles without glaucoma were identified from patients of the Aravind Eye Hospital in Pondicherry, India. One or more siblings of the probands were also recruited to participate in the study. Participants underwent A-scan ultrasonography to measure ocular dimension components. Heritabilities of axial length (AL), anterior chamber depth (ACD), lens thickness (LT), and ocular refraction (REF) were estimated individually and simultaneously using structural equation modeling (SEM). Age and sex structural effects were also included in the models.
189 sibling pairs with complete data were available for analysis. In single-factor measurement model analyses, the heritabilities of AL, ACD, LT and REF were .68, .13, .6 and .28, respectively. When simultaneously modeled with putative structural dependencies between measured variables specified in the models, the heritabilities for AL, ACD, LT and REF were .66, .4, .46 and .36.
Our results suggest that modeling the genetic parameters of ocular biometric components independently can lead to considerable differences in heritability estimates compared to simultaneously modeling all variables. The direction of the resulting bias will depend on the choice of structural model and on the true underlying covariance structure. SEM offers a method to simultaneously model the genetic effects of structurally-dependent variables and can be adapted to both linkage and association studies.
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