Linkage disequilibrium refers to the association between alleles at different loci. The standard definition applies to two alleles in the same gamete, and it can be regarded as the covariance of indicator variables for the states of those two alleles. The corresponding correlation coefficient rho is the parameter that arises naturally in discussions of tests of association between markers and genetic diseases. A general treatment of association tests makes use of the additive and nonadditive components of variance for the disease gene. In almost all expressions that describe the behavior of association tests, additive variance components are modified by the squared correlation coefficient rho2 and the nonadditive variance components by rho4, suggesting that nonadditive components have less influence than additive components on association tests.

中文翻译：

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连锁不平衡和关联映射。

连锁不平衡是指在不同基因座的等位基因之间的关联。标准定义适用于同一配子中的两个等位基因，可以将其视为这两个等位基因状态的指示变量的协方差。相应的相关系数rho是在标记与遗传疾病之间的关联测试的讨论中自然产生的参数。关联测试的一般方法是利用疾病基因变异的加性和非加性成分。在几乎所有描述关联测试行为的表达式中，加性方差成分均由平方相关系数rho2修改，非加性方差成分均由rho4修改，这表明非加性成分对关联性测试的影响小于加性成分。