RECONSTRUCTING GENETIC ANCESTRY BLOCKS IN ADMIXED INDIVIDUALS

该子项目是利用 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得主要资金， 因此可以在其他CRISP条目中表示。列出的机构是 中心，不一定是研究者的机构。 一个最近混合祖先的个体的染色体类似于一个染色体片段或祖先块的镶嵌，每个片段或块都来自一个特定的祖先群体。我们考虑的问题，推断祖先沿着染色体在一个混合的个人，从而划定祖先块。使用一个简单的人口模型，我们推断每个人的基因流历史。与基于隐马尔可夫模型的现有方法相比，隐马尔可夫模型（MHMM），我们提出的优势，占背景连锁不平衡（LD）存在于祖先群体。当有两个以上的祖先群体时，我们允许每个祖先群体在历史的不同时期混合。我们使用模拟来说明推断的祖先的准确性以及建模的背景LD的重要性;不考虑标记之间的背景LD可能会误导我们对土著人口中混合祖先的错误推断。MHMM使得通过使用任何高密度的单核苷酸序列来识别特定祖先的基因组块成为可能。多态性组。我们的方法的一个应用是进行混合作图，而不需要基因分型特殊的祖先信息。标记面板。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. A chromosome in an individual of recently admixed ancestry resembles a mosaic of chromosomal segments, or ancestry blocks, each derived from a particular ancestral population. We consider the problem of inferring ancestry along the chromosomes in an admixed individual and thereby delineating the ancestry blocks. Using a simple population model, we infer gene-flow history in each individual. Compared with existing methods, which are based on a hidden Markov model, the Markovhidden Markov model (MHMM) we propose has the advantage of accounting for the background linkage disequilibrium (LD) that exists in ancestral populations. When there are more than two ancestral groups, we allow each ancestral population to admix at a different time in history. We use simulations to illustrate the accuracy of the inferred ancestry as well as the importance of modeling the background LD; not accounting for background LD between markers may mislead us to false inferences about mixed ancestry in an indigenous population. The MHMM makes it possible to identify genomic blocks of a particular ancestry by use of any high-density single-nucleotidepolymorphism panel. One application of our method is to perform admixture mapping without genotyping special ancestry-informativemarker panels.