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Heritability and shared environment estimates for myopia and associated ocular biometric traits: the Genes in Myopia (GEM) family study

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Chen, CY and Scurrah, KJ and Stankovich, J and Garoufalis, P and Dirani, M and Pertile, KK and Richardson, AJ and Mitchell, P and Baird, PN (2007) Heritability and shared environment estimates for myopia and associated ocular biometric traits: the Genes in Myopia (GEM) family study. Human Genetics, 121 (3 - 4). pp. 511-520. ISSN 0340-6717

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Abstract

To examine the familial correlations, heritability
(h2) and common environmental components
(c2) of myopia and ocular biometric traits (all treated
as continuous outcomes) in families collected through
the Genes in Myopia (GEM) family study in Australia.
A total of 132 pedigrees (723 participants) were recruited
for this study. All individuals completed a risk
factor questionnaire and underwent a detailed eye
examination including spherical equivalent (SphE) and
ocular biometric measurements of axial length (AL),
anterior chamber depth (ACD) and corneal curvature
(CC). Familial correlations were calculated and h2 and
c2 were estimated using a variance component model
that assumes a multivariate t distribution within each
pedigree. Two definitions of common environments
(c2) were considered: nuclear family (current) shared
environment (Model 1) and sib-ship (childhood)
shared environment (Model 2). Population ascertainment
adjustment was performed using the Blue
Mountains eye study dataset. The trends observed for
familial correlations suggested that SphE is influenced
by both environmental and genetic factors whereas
AL, ACD and CC are predominantly genetically
determined. This was largely confirmed by variance
components modelling. Heritability estimates (adjusted
for age, sex and years of education) from the
best fitting ACE model (Model 2, childhood shared
environment) were 0.50 ± 0.05 for SphE, 0.73 ± 0.04
for AL, 0.78 ± 0.04 for ACD and 0.16 ± 0.06 for CC.
Childhood environmental effects were significant with
c2 estimated to be 0.33 ± 0.04 for SphE, 0.06 ± 0.03 for
AL, 0.22 ± 0.04 for ACD and 0.10 ± 0.05 for CC. Age
was associated with SphE, total years of education was
associated with AL and sex was associated with all
traits studied. We used a novel and conservative approach
to account for and estimate common environmental
effects by specifying either nuclear family or
sib-ship environment when estimating heritability
estimates and showed that all traits examined (SphE,
AL, ACD and CC) are heritable, thus reflecting a genetic
component. These traits therefore all represent
candidates for quantitative trait linkage analyses.

Item Type: Article
Keywords: Myopia Ocular biometrics Familial correlation Heritability Common environment
Journal or Publication Title: Human Genetics
Publisher: Springer
Page Range: pp. 511-520
ISSN: 0340-6717
Identification Number - DOI: 10.1007/s00439-006-0312-0
Additional Information:

The original publication is available at www.springerlink.com

Date Deposited: 07 Apr 2008 14:12
Last Modified: 18 Nov 2014 03:33
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