Heiba I M, Elston R C, Klein B E, Klein R
Department of Biometry and Genetics, Louisiana State University Medical Center, New Orleans 70112-1393.
Invest Ophthalmol Vis Sci. 1995 Jan;36(1):227-35.
To examine the possible presence of a major gene determining susceptibility to cortical cataract.
The percentage of the lens area involved with cortical opacity, summed over both eyes, was evaluated in 1275 individuals from the Beaver Dam Eye Study. After adjusting for the effects of age and sex, these measures of cortical cataract were subjected to sibling correlational analysis, commingling analysis, and segregation analysis. The Box and Cox power transformation was applied to the data for the commingling and segregation analyses. Using regressive models, four modes of transmission were examined, and under each mode three hypotheses and a general model were fitted by maximum likelihood and compared.
Sister-sister and brother-brother correlations of the adjusted measures of cortical cataract are significant and similar; the brother-sister correlation is not significantly different either from these correlations or from zero. Two commingled distributions give the best fit to the data, especially after power transformation. Under each of four modes of transmission, the hypothesis that best fits the data is one in which there are only two distributions (and, hence, dominance under mendelian transmission), the power transformation parameter is fixed at the estimate obtained from commingling analysis, and there is residual sibling correlation. The data thus suggest the existence of a major effect for cortical cataract. Random environmental influences can be rejected as a cause of this major effect. Our analysis indicates the existence of a significant effect of sex on the residual variance. Allowing for this, the data suggest transmission of a single major gene, though this may not be the sole cause of the commingled distributions.
Assuming a common variance for the two sexes, a single major gene can account for 58% of the variability of age- and sex-adjusted measures of cortical cataract. With the variance sex dependent, a major gene can account for 75% and 45% of the total variability among males and females, respectively.
研究是否可能存在决定皮质性白内障易感性的主基因。
对来自比弗迪姆眼研究的1275名个体，评估双眼皮质混浊累及的晶状体面积百分比。在调整年龄和性别影响后，对这些皮质性白内障指标进行同胞相关性分析、混合分析和分离分析。对混合分析和分离分析的数据应用Box和Cox幂变换。使用回归模型，检验四种传递模式，在每种模式下，通过最大似然法拟合三个假设和一个通用模型并进行比较。
调整后的皮质性白内障指标在姐妹间和兄弟间的相关性显著且相似；兄妹间的相关性与这些相关性或与零均无显著差异。两种混合分布对数据拟合最佳，尤其是在幂变换后。在四种传递模式中的每一种下，最符合数据的假设是只有两种分布（因此，在孟德尔遗传传递下存在显性），幂变换参数固定在从混合分析中获得的估计值，并且存在残余同胞相关性。因此，数据表明存在对皮质性白内障的主要影响。随机环境影响可被排除为这种主要影响的原因。我们的分析表明性别对残余方差有显著影响。考虑到这一点，数据表明存在一个单一主基因的传递，尽管这可能不是混合分布的唯一原因。
假设两性的方差相同，一个单一主基因可解释年龄和性别调整后的皮质性白内障指标变异性的58%。若方差依赖于性别，一个主基因可分别解释男性和女性总变异性的75%和45%。
