Pleiotropy (whereby one genetic polymorphism affects multiple traits) and epistasis (whereby non-linear interactions between genetic polymorphisms affect the same trait) are fundamental aspects of the genetic architecture of quantitative traits. Recent advances in the ability to characterize the effects of polymorphic variants on molecular and organismal phenotypes in human and model organism populations have revealed the prevalence of pleiotropy and unexpected shared molecular genetic bases among quantitative traits, including diseases. By contrast, epistasis is common between polymorphic loci associated with quantitative traits in model organisms, such that alleles at one locus have different effects in different genetic backgrounds, but is rarely observed for human quantitative traits and common diseases. Here, we review the concepts and recent inferences about pleiotropy and epistasis, and discuss factors that contribute to similarities and differences between the genetic architecture of quantitative traits in model organisms and humans.

多效性（一种遗传多态性影响多个性状）和上位性（遗传多态性之间的非线性相互作用影响同一性状）是数量性状遗传结构的基本方面。在描述多态性变异对人类和模式生物群体的分子和生物表型的影响方面的最新进展揭示了包括疾病在内的数量性状中普遍存在的多效性和意想不到的共享分子遗传基础。相比之下，模式生物中与数量性状相关的多态位点之间常见上位性，即一个位点的等位基因在不同遗传背景下具有不同的作用，但在人类数量性状和常见疾病中很少观察到。在这里，我们回顾了有关多效性和上位性的概念和最新推论，并讨论了导致模式生物和人类数量性状遗传结构之间相似和差异的因素。