Prescott C A, Johnson R C, McArdle J J
Virginia Institute for Psychiatric and Behavioral Genetics, Department of Psychiatry, Virginia Commonwealth University, Richmond 23298, USA.
Twin Res. 1999 Dec;2(4):244-9. doi: 10.1375/136905299320565726.
The estimation of genetic effects from twin studies usually relies upon the equal environment assumption--that monozygous (MZ) and dizygous (DZ) twin pairs experience equal similarity of their environments from prenatal experiences through adulthood. However, the sharing of a chorion may make a subset of identical twins more similar, or in some cases, more different, than twins that do not share a chorion. Recent studies suggest monochorionic MZ twins resemble one another more than dichorionic MZ twins in cognitive abilities, personality, and risk for psychiatric disorder. To the extent that prenatal environment affects these characteristics, the traditional twin method will yield biased estimates of genetic and environmental influences. We develop models for quantifying this bias and estimating the influence of chorion type on estimates of heritability.
双胞胎研究中对遗传效应的估计通常依赖于等环境假设，即同卵（MZ）和异卵（DZ）双胞胎对从产前经历到成年期的环境具有相同的相似性。然而，共用一个绒毛膜可能会使一部分同卵双胞胎比不共用绒毛膜的双胞胎更加相似，或者在某些情况下更加不同。最近的研究表明，单绒毛膜MZ双胞胎在认知能力、个性和精神疾病风险方面比双绒毛膜MZ双胞胎彼此更相似。就产前环境影响这些特征而言，传统的双胞胎方法将对遗传和环境影响产生有偏差的估计。我们开发了模型来量化这种偏差，并估计绒毛膜类型对遗传力估计的影响。
