Wadsworth Sally J, DeFries John C
Institute for Behavioral Genetics, University of Colorado, Boulder, Colorado 80309, USA.
Twin Res Hum Genet. 2005 Dec;8(6):594-601. doi: 10.1375/183242705774860196.
Although it has been suggested that genetic influences on reading difficulties may differ in boys and girls, results obtained from previous analyses of data from same-sex twin pairs have failed to provide evidence for a differential genetic etiology of reading disability (RD) as a function of gender. However, results of a recent study in which data from both same-sex and opposite-sex twin pairs were analyzed indicated a higher heritability for reading difficulties in boys (Harlaar et al., 2005). Because the current sample of twin pairs tested in the Colorado Learning Disabilities Research Center is substantially larger than that analyzed for our previous report (Wadsworth et al., 2000), this hypothesis was tested more rigorously using data from both same-sex and opposite-sex twin pairs in our current augmented sample. Composite reading scores from 634 twin pairs were subjected to DeFries-Fulker sex-limitation analysis using the model-fitting approach of Purcell and Sham (2003). Analysis of data from the combined sample of male and female twins indicated that genetic influences account for more than half the proband reading deficit (h2g = .58). When this model was extended to test for gender differences in the magnitude of genetic influences on RD, h2g estimates were somewhat higher for females than for males (.63 and .53, respectively), but the difference was nonsignificant (p > .3). A test for qualitative gender differences was also nonsignificant. Thus, these results provide little evidence for a differential genetic etiology of RD in boys and girls.
尽管有人提出，遗传因素对阅读困难的影响在男孩和女孩中可能有所不同，但先前对同性双胞胎数据进行分析所得到的结果，未能为阅读障碍（RD）因性别而异的遗传病因提供证据。然而，最近一项对同性和异性双胞胎数据均进行分析的研究结果表明，男孩阅读困难的遗传度更高（哈拉尔等人，2005年）。由于科罗拉多学习障碍研究中心目前所测试的双胞胎样本，比我们先前报告（沃兹沃思等人，2000年）所分析的样本要大得多，因此，我们使用当前扩大样本中的同性和异性双胞胎数据，对这一假设进行了更严格的检验。对634对双胞胎的综合阅读分数，采用珀塞尔和沙姆（2003年）的模型拟合方法，进行德弗里斯-富尔克性别限制分析。对男性和女性双胞胎的合并样本数据进行分析表明，遗传因素占先证者阅读缺陷的一半以上（h2g = 0.58）。当扩展该模型以检验遗传因素对阅读障碍影响程度的性别差异时，女性的h2g估计值略高于男性（分别为0.63和0.53），但差异不显著（p > 0.3）。对质性性别差异的检验也不显著。因此，这些结果几乎没有为男孩和女孩阅读障碍的遗传病因差异提供证据。
