de Vries André R, te Meerman Gerard J
Department of Genetics, University Medical Center Groningen and University of Groningen, Groningen, The Netherlands.
Hum Hered. 2010;69(1):52-9. doi: 10.1159/000243154. Epub 2009 Oct 2.
There are two aspects regarding the age of alleles that are relevant as indicators of the timing of mutational events. The first is to know which alleles are species-specific; the second is about the time of origin of species-specific alleles. Both aspects can be analyzed using haplotype-sharing methods, by using the length of shared haplotypes as a measure of the speed of coalescence to common ancestors. The availability of sequence data for closely related species makes it possible to infer the original SNP allele. The allele present in more than one species is the original allele. In general, original alleles are expected to be more frequent, because the cumulative effects of genetic drift determine the maximum frequency a new mutant can reach. The human species is relatively young, and founder effects are still observable as extended linkage disequilibrium. Coalescence to a single founder takes place in human populations over a time frame that is so small that original haplotypes spanning several markers are still observable in current high-density SNP genotyping arrays. We show here that the length of shared haplotypes surrounding alleles is an indicator of the relative ages of alleles, and it is applicable to original and species-specific alleles.
关于等位基因的年龄有两个方面与突变事件发生时间的指标相关。第一个方面是要知道哪些等位基因是物种特异性的；第二个方面是关于物种特异性等位基因的起源时间。这两个方面都可以使用单倍型共享方法进行分析，通过将共享单倍型的长度作为衡量向共同祖先合并速度的指标。密切相关物种的序列数据的可用性使得推断原始单核苷酸多态性（SNP）等位基因成为可能。存在于多个物种中的等位基因就是原始等位基因。一般来说，原始等位基因预计会更常见，因为遗传漂变的累积效应决定了新突变所能达到的最大频率。人类物种相对年轻，奠基者效应仍可作为扩展的连锁不平衡观察到。在人类群体中，向单个奠基者的合并发生在一个非常短的时间框架内，以至于在当前的高密度SNP基因分型阵列中仍然可以观察到跨越多个标记的原始单倍型。我们在此表明，等位基因周围共享单倍型的长度是等位基因相对年龄的一个指标，并且它适用于原始等位基因和物种特异性等位基因。
