Department of Ophthalmology and Visual Sciences, University of Iowa Hospitals and Clinics, Iowa City, Iowa 52242, USA.
Invest Ophthalmol Vis Sci. 2010 Nov;51(11):5870-7. doi: 10.1167/iovs.10-5527. Epub 2010 May 26.
Discovery and description of heritable optic nerve head (ONH) phenotypes have been haphazard. In this preliminary study, the authors test the hypothesis that inheritable phenotypes can be discovered and quantified computationally by estimating three-dimensional ONH shape parameters from stereo color photographs from the Twins Eye Study in Tasmania and determining how much of the variability in ONH shape is accounted for by genetic influence.
Three-dimensional ONH shape was estimated by an automated algorithm from stereoscopic optic disc color photographs of a random sample of 172 subjects (344 eyes, 45 pairs of monozygotic [MZ] and 41 dizygotic [DZ] twins). Shape resemblances between eyes were quantified with a distance metric. The heritability of the shape resemblance was determined both through the distribution of the discongruence indices and through structural equation modeling techniques (ACE model).
Significantly different discongruence indices were found for MZ (1.0286; 95% CI, 0.9872-1.0701) and DZ twins (1.4218; 95% CI, 1.2631-1.5804); larger indices for DZ twins indicated that variability was substantially determined by genetic factors. The standardized variances of the A(dditive genetic), C(ommon environmental), and (nonshared) E(nvironmental) components were 0.80, 2.00 × 10(-15) and 0.20, respectively, for all OD, and 0.79, 3.24 × 10(-14), and 0.21 for all OS.
This preliminary study shows that quantitative phenotyping of the ONH shape from color images leads to phenotypes that can be measured and are largely under genetic control. The association of these inherited phenotypes with genotypes deserves confirmation and further study.
遗传视神经头（ONH）表型的发现和描述一直很随意。在这项初步研究中，作者通过从塔斯马尼亚双胞胎研究的立体彩色照片中估计 ONH 形状参数，并确定遗传影响对 ONH 形状变化的解释程度，来检验遗传表型可以通过计算方法发现和量化的假设。
从 172 名受试者（344 只眼睛，45 对同卵双胞胎[MZ]和 41 对异卵双胞胎[DZ]）的立体视盘彩色照片中，使用自动算法估计了 ONH 的三维形状。通过距离度量来量化眼睛之间的形状相似性。通过离散指数的分布和结构方程建模技术（ACE 模型）来确定形状相似性的遗传力。
MZ（1.0286；95%置信区间，0.9872-1.0701）和 DZ 双胞胎（1.4218；95%置信区间，1.2631-1.5804）的离散指数存在显著差异；DZ 双胞胎的离散指数较大表明，变异性主要由遗传因素决定。所有 OD 的 A（加性遗传）、C（共同环境）和（非共享）E（环境）成分的标准化方差分别为 0.80、2.00×10(-15)和 0.20，所有 OS 的标准化方差分别为 0.79、3.24×10(-14)和 0.21。
这项初步研究表明，从彩色图像中对 ONH 形状进行定量表型分析可以得出可以测量且主要受遗传控制的表型。这些遗传表型与基因型的关联值得进一步确认和研究。
