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The path to open-angle glaucoma gene discovery: Endophenotypic status of intraocular pressure, cup-to-disc ratio, and central corneal thickness


Charlesworth, J and Kramer, PL and Dyer, T and Diego, V and Samples, JR and Craig, JE and Mackey, DA and Hewitt, AW and Blangero, J and Wirtz, MK, The path to open-angle glaucoma gene discovery: Endophenotypic status of intraocular pressure, cup-to-disc ratio, and central corneal thickness, Investigative Ophthalmology and Visual Science, 51, (7) pp. 3509-3514. ISSN 0146-0404 (2010) [Refereed Article]

DOI: doi:10.1167/iovs.09-4786


Purpose: Primary open-angle glaucoma (POAG) is a complex disease with a genetic architecture that can be simplified through the investigation of individual traits underlying disease risk. It has been well studied in twin models, and this study was undertaken to investigate the heritability of some of these key endophenotypes in extended pedigrees.

Methods: These data are derived from a large, multicenter study of extended, Caucasian POAG families from Australia and the United States. The study included 1181 people from 22 extended pedigrees. Variance components modeling was used to determine the heritabilities of maximum intraocular pressure (IOP), maximum vertical cup-to-disc ratio (VCDR), and mean central corneal thickness (CCT). Bivariate quantitative genetic analysis between these eye-related phenotypes and POAG itself was performed to determine whether any of these traits represent true endophenotypes.

Results: Heritability estimates for IOP, VCDR, and CCT (0.42, 0.66, and 0.72, respectively) were significant and show strong concordance with data in previous studies. Bivariate analysis revealed that both IOP (RhoG = 0.80; P = 9.6 X 10-6) and VCDR (RhoG = 0.76; P = 4.8 X 10-10) showed strong evidence of genetic correlation with POAG susceptibility. These two traits also correlated genetically with each other (RhoG = 0.45; P = 0.0012). Alternatively, CCT did not correlate genetically with risk of POAG.

Conclusions: All the proposed POAG-related traits have genetic components. However, the significant genetic correlations observed between IOP, VCDR, and POAG itself suggest that they most likely represent true endophenotypes that could aid in the identification of genes underlying POAG susceptibility. CCT did not correlate genetically with disease and is unlikely to be a useful surrogate endophenotype for POAG.

Item Details

Item Type:Refereed Article
Research Division:Biomedical and Clinical Sciences
Research Group:Ophthalmology and optometry
Research Field:Vision science
Objective Division:Health
Objective Group:Clinical health
Objective Field:Clinical health not elsewhere classified
UTAS Author:Charlesworth, J (Dr Jac Charlesworth)
UTAS Author:Mackey, DA (Professor David Mackey)
UTAS Author:Hewitt, AW (Professor Alex Hewitt)
ID Code:67871
Year Published:2010
Web of Science® Times Cited:75
Deposited By:Medicine
Deposited On:2011-03-08
Last Modified:2014-10-06

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