Astrom Raven L, Wadsworth Sally J, DeFries John C
Institute for Behavioral Genetics, Department of Psychology, University of Colorado, Boulder, Colorado 80309, United States of America.
Twin Res Hum Genet. 2007 Jun;10(3):434-9. doi: 10.1375/twin.10.3.434.
Results obtained from previous longitudinal studies of reading difficulties indicate that reading deficits are generally stable. However, little is known about the etiology of this stability. Thus, the primary objective of this first longitudinal twin study of reading difficulties is to provide an initial assessment of genetic and environmental influences on the stability of reading deficits. Data were analyzed from a sample of 56 twin pairs, 18 identical (monozygotic, MZ) and 38 fraternal (dizygotic, DZ), in which at least one member of each pair was classified as reading-disabled in the Colorado Learning Disabilities Research Center, and on whom follow-up data were available. The twins were tested at two time points (average age of 10.3 years at initial assessment and 16.1 years at follow-up). A composite measure of reading performance (PIAT Reading Recognition, Reading Comprehension and Spelling) was highly stable, with a stability correlation of .84. Data from the initial time point were first subjected to univariate DeFries-Fulker multiple regression analysis and the resulting estimate of the heritability of the group deficit (h2g) was .84 (+/-.26). When the initial and follow-up data were then fitted to a bivariate extension of the basic DF model, bivariate heritability was estimated at .65, indicating that common genetic influences account for approximately 75% of the stability between reading measures at the two time points.
先前关于阅读困难的纵向研究结果表明，阅读缺陷通常是稳定的。然而，对于这种稳定性的病因知之甚少。因此，这项关于阅读困难的首次纵向双胞胎研究的主要目标是初步评估遗传和环境因素对阅读缺陷稳定性的影响。对56对双胞胎的数据进行了分析，其中18对同卵双胞胎（单卵双生，MZ）和38对异卵双胞胎（双卵双生，DZ），每对双胞胎中至少有一名成员在科罗拉多学习障碍研究中心被归类为阅读障碍者，并且有随访数据。这些双胞胎在两个时间点接受了测试（初次评估时的平均年龄为10.3岁，随访时为16.1岁）。阅读表现的综合测量指标（PIAT阅读识别、阅读理解和拼写）非常稳定，稳定性相关系数为0.84。首先对初始时间点的数据进行单变量DeFries-Fulker多元回归分析，得出的群体缺陷遗传率估计值（h2g）为0.84（±0.26）。然后，将初始数据和随访数据拟合到基本DF模型的双变量扩展模型中，双变量遗传率估计为0.65，这表明共同的遗传影响约占两个时间点阅读测量指标之间稳定性的75%。
