有害突变基因在有限群体中的首次出现时间和平均年龄。
The first arrival time and mean age of a deleterious mutant gene in a finite population.
作者信息
Li W H
机构信息
Center for Demographic and Population Genetics, University of Texas, Houston 77025.
出版信息
Am J Hum Genet. 1975 May;27(3):274-86.
The mean and standard deviation of the first arrival time for a single mutant to reach a certain frequency and the mean age of a mutant persisting in a population have been studied using diffusion methods. These quantities are shown to be highly dependent on both the heterozygous effect and the population size. For partially recessive deleterious mutations, both the mean first arrival time and the mean age decrease with increasing selection coefficient against heterozygotes. For overdominant mutations, the mean age always increases very rapidly with increasing heterozygous advantage, while the mean first arrival time first increases rapidly with increasing heterozygous advantage to a maximum and then decreases rapidly with increasing heterozygous advantage. The standard deviation of the first arrival time is small while that of the age is large. The results of this study have been applied to study the case of the sickle cell anemia mutant in Africa. It is argued that the present prevalence may be explained without the necessity of quite so great a heterozygous advantage as .25 or higher as proposed by some workers. A reasonable range for the heterozygous advantage seems to be from .05 to .18.
利用扩散方法研究了单个突变体达到特定频率的首次到达时间的均值和标准差，以及突变体在群体中持续存在的平均年龄。结果表明，这些量高度依赖于杂合效应和群体大小。对于部分隐性有害突变，平均首次到达时间和平均年龄均随着针对杂合子的选择系数增加而降低。对于超显性突变，平均年龄总是随着杂合优势增加而迅速增加，而平均首次到达时间则随着杂合优势增加先迅速增加至最大值，然后随着杂合优势增加而迅速降低。首次到达时间的标准差较小，而年龄的标准差较大。本研究结果已应用于研究非洲镰状细胞贫血突变体的情况。有人认为，目前的患病率可以得到解释，而无需像一些研究人员所提出的那样具有高达0.25或更高的杂合优势。杂合优势的合理范围似乎是0.05至0.18。
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