He Mingguang, Wang Dandan, Console James W, Zhang Jian, Zheng Yingfeng, Huang Wenyong
State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China.
Invest Ophthalmol Vis Sci. 2009 Apr;50(4):1593-7. doi: 10.1167/iovs.08-2735. Epub 2008 Dec 5.
To investigate the distribution and heritability of iris thickness and pupil diameter measured by anterior segment optical coherence tomography (ASOCT) in a classic twin study.
Twins aged 8 to 16 years were enrolled from the Guangzhou Twin Registry. ASOCT was used to obtain one horizontal scan, and the images were analyzed with custom software. Iris thickness was measured at 750 microm (IT750) and 2000 microm (IT2000) from the scleral spur, as well as cumulative iris area (IAREA). Pupil diameter in millimeters (PDMM) was measured between the most central points of the iris at the nasal and temporal sides. Zygosity was confirmed by genotyping in all same-sex twin pairs. Heritability was assessed by structural variance component genetic modeling after adjustment for age and sex with the Mx program.
Participating in the analysis were 309 monozygotic (MZ) and 165 dizygotic (DZ) twin pairs. The mean IT750, IT2000, and IAREA were 0.406+/-0.075 (SD) mm, 0.514+/-0.075 mm, and 1.169+/-0.184 mm(2), whereas the PDMM was 5.600+/-0.0821 mm. The intraclass correlation coefficients for the IT750, IT2000, IAREA, and PDMM were 0.53, 0.54, 0.61, and 0.63 for MZ pairs and 0.29, 0.11, 0.35, and 0.34 for DZ pairs, respectively. A model with additive genetic and unique environmental effect was the most parsimonious, and the heritability was approximately 60% for iris thickness and pupil diameter.
Iris thickness is thinner in girls but is not associated with age in children. The variation is largely attributable to additive genetic effects.
在一项经典双生子研究中，通过眼前节光学相干断层扫描（ASOCT）研究虹膜厚度和瞳孔直径的分布及遗传度。
从广州双生子登记处招募8至16岁的双生子。使用ASOCT获取一次水平扫描图像，并用定制软件进行分析。从巩膜突测量750微米（IT750）和2000微米（IT2000）处的虹膜厚度，以及累积虹膜面积（IAREA）。以毫米为单位（PDMM）测量虹膜鼻侧和颞侧最中心点之间的瞳孔直径。通过对所有同性双生子对进行基因分型来确定合子性。使用Mx程序在对年龄和性别进行调整后，通过结构方差成分遗传模型评估遗传度。
参与分析的有309对同卵双生子（MZ）和165对异卵双生子（DZ）。IT750、IT2000和IAREA的平均值分别为0.406±0.075（标准差）毫米、0.514±0.075毫米和1.169±0.184平方毫米，而PDMM为5.600±0.0821毫米。MZ对中IT750、IT2000、IAREA和PDMM的组内相关系数分别为0.53、0.54、0.61和0.63，DZ对中分别为0.29、0.11、0.35和0.34。具有加性遗传和独特环境效应的模型最为简约，虹膜厚度和瞳孔直径的遗传度约为60%。
女孩的虹膜厚度较薄，但与儿童年龄无关。这种变异很大程度上归因于加性遗传效应。
