THE POWER OF THE CLASSICAL TWIN STUDY TO RESOLVE VARIATION IN THRESHOLD TRAITS
THE POWER OF THE CLASSICAL TWIN STUDY TO RESOLVE VARIATION IN THRESHOLD TRAITS
复制标题
DOI：
10.1007/bf01067191
复制
发表时间：
1994-05-01
影响因子：
2.6
通讯作者：
KENDLER, KS
中科院分区：
文献类型：
--
作者：
NEALE, MC;EAVES, LJ;KENDLER, KS
当数据在二元或序数水平上测量时，我们探索双胞胎研究解决家族相似性来源的力量。检查了方差的四个组成部分：加性遗传、非加性遗传以及共同和特定环境。曲线用于比较连续病例的功效与对应于人群中不同患病率的阈值模型的功效：1,5,10,25 和 50%。当阈值处于最佳 50% 时，大约需要三倍的样本量才能达到连续情况的等效功效，而当 10% 高于阈值时，该比率会增加到大约 10 倍。通过将阈值以上的功率细分以形成三个或更多有序类别，可以恢复一些功率，但功率主要由最低阈值决定。双胞胎的非随机确定；（i）通过受影响的双胞胎并检查其双胞胎或（ii）通过确定至少一个双胞胎受影响的所有对来增加功效。在大多数情况下，策略 i 比策略 ii 更有效。尽管这些方法对于罕见疾病很有效，但其缺点是它们依赖于人群患病率的先验知识。此外，从医院病例中抽样可能会引入偏差，从而降低其价值。一种有用的方法可能是使用筛查工具对人群进行评估；功效计算表明，只要筛选成本不太高，对所有一致对和一半不一致对进行采样将是有效的。
We explore the power of the twin study to resolve sources of familial resemblance when the data are measured at the binary or ordinal level. Four components of variance were examined: additive genetic, nonadditive genetic, and common and specific environment. Curves are Presented to compare the power of the continuous case with those of threshold models corresponding to different prevalences in the population: 1,5, 10, 25, and 50%. Approximately three times the sample size is needed for equivalent power to the continuous case when the threshold is at the optimal 50%, and this ratio increases to about 10 times when 10% are above threshold. Some power may be recovered by subdividing those above threshold to form three or more ordered classes, but power is determined largely by the lowest threshold. Non-random ascertainment of twins;(i) through affected twins and examining their cotwins or (ii) through ascertainment of all pairs in which at least one twin is affected increases power. In most cases, strategy i is more efficient than strategy ii. Though powerful for the rarer disorders, these methods suffer the disadvantage that they rely on prior knowledge of the population prevalence. Furthermore, sampling from hospital cases may introduce biases, reducing their value. A useful approach may be to assess the population with a screening instrument; the power calculations indicate that sampling all concordant and half of the discordant pairs would be efficient, as along as the cost of screening is not too high.