Forsberg Christopher W, Goldberg Jack, Sporleder Jennifer, Smith Nicholas L
Department of Veterans Affairs Office of Research and Development, Seattle, WA, USA.
Twin Res Hum Genet. 2010 Oct;13(5):461-4. doi: 10.1375/twin.13.5.461.
Our work assessed the accuracy of the original zygosity classification in the Vietnam Era Twin (VET) Registry using new information from DNA markers on a subset of participants. We then constructed an updated zygosity classification algorithm. The VET Registry includes 7,375 male-male twin pairs who served in the military during the Vietnam era. During the mid-1980s 4,774 twin pairs completed a zygosity questionnaire of 20 items. Additionally, military record information, including blood group, was available. Items from the zygosity questionnaire and blood group were used in the original zygosity classification. Between 1990-2009 DNA was obtained from 612 twin pairs and concordance between co-twins was used to classify zygosity. Next logistic regression was used to construct predicted probabilities of zygosity using items from the zygosity questionnaire with this subsample. All twins were reclassified according to the new zygosity prediction model and compared with the original zygosity assignment. The original and new predicted probabilities of zygosity were highly correlated (r = 0.962) and concordance for the classification of zygosity was similarly high (kappa = 0.936). Errors in the original zygosity assignment were primarily due to monozygotic twins that were misclassified as dizygotic based on military record blood group data. Removing the military record blood group data markedly improved the accuracy of the original classification. Zygosity assignment based on a zygosity questionnaire was highly predictive of DNA-based zygosity. Augmentation of such a zygosity classification from administrative data, military records, or other records, should be done with caution.
我们的研究利用部分参与者的DNA标记新信息，评估了越南时代双胞胎（VET）登记处原始合子性分类的准确性。然后，我们构建了一个更新的合子性分类算法。VET登记处包括7375对在越南战争期间服役的男性双胞胎。在20世纪80年代中期，4774对双胞胎完成了一份包含20个条目的合子性问卷。此外，还可获取包括血型在内的军事记录信息。原始合子性分类使用了合子性问卷中的条目和血型信息。1990年至2009年间，从612对双胞胎中获取了DNA，并利用双胞胎之间的一致性来对合子性进行分类。接下来，使用逻辑回归，利用该子样本中合子性问卷的条目构建合子性的预测概率。所有双胞胎都根据新的合子性预测模型重新分类，并与原始合子性分类进行比较。合子性的原始预测概率和新预测概率高度相关（r = 0.962），合子性分类的一致性同样很高（kappa = 0.936）。原始合子性分类中的错误主要是由于同卵双胞胎根据军事记录血型数据被误分类为异卵双胞胎。去除军事记录血型数据显著提高了原始分类的准确性。基于合子性问卷的合子性分类对基于DNA的合子性具有高度预测性。从行政数据、军事记录或其他记录中增强此类合子性分类时应谨慎行事。
