Devising a multiplex DNA typing system to identify the third-degree kinship

通过DNA分析得出两个人是三级亲属(例如表亲)的结论是一项艰巨的任务，因为据称的个人在任何给定的基因座上共享共同等位基因的可能性只有25%。为了增加这种关系的确定性，专家们经常求助于高变量的小卫星基因座，因为一对个体在拥有罕见等位基因的情况下可以表现出很高的似然比(LRs)。我们首先研究了泰国、中国汉族和日本人群的等位基因结构的比较。绝大多数可配对的亚洲等位基因在亚洲显示出最接近的结构亲缘关系。因此，这颗快速进化的小卫星可以作为一种谱系标记，用于探索人类种群历史上的最新事件，并在精细水平上解剖种群结构，以及作为一种极其信息量的DNA标记来进行个人身份识别。然后，我们检查了两组兄弟姐妹…的三级亲属更多的是使用两个高变数的小卫星基因座。由于两组之间没有共享等位基因，因此没有建立关系；尽管两组之间的等位基因共享程度适中。我们还估计了LRs在各种亲属关系(亲子、兄弟姐妹、两个S！Iblings等)使用可同时扩增15个STR基因座的商用打字试剂盒。尽管在父母双方或两个或两个以上子女(或兄弟姐妹)可以进行比较的情况下，STR系统在确定个人身份方面非常有用，但该系统在三级亲属关系分析中有效的可能性很小。这一假设是基于我们对已知三级亲属样本的研究，在该研究中，我们尝试了一种基于微卫星的方法来建立亲属关系。然而，不幸的是，仅就微卫星而言，计算的LR小于1，这不足以进行阳性识别。因此，一种更有效的方法，如估计染色体共享的比例，将比试图证明几个基因座的等位基因高度变异性更有利。到目前为止，我们已经分析了分布在整个人类基因组中的382个二核苷酸基因座，以估计在不同血缘关系模式下两个个体共享单倍型的长度比例。我们获得的初步数据是有希望的，目前正在仔细分析。较少

Arriving at a conclusion that two individuals are third degree relatives (e.g. cousin) via DNA analysis is a difficult task as the purported individuals have only a 25% chance of sharing common alleles at any given locus. In order to increase the certainty of the relationship, experts often resort to hypervariable minisatellite loci because a pair of individuals can demonstrate high likelihood ratios (LRs) in the event that they share rare alleles. We firstly investigated the comparison of allele structures in Thai, Han Chinese, and Japanese populations. The great majority of alignable Asian alleles showed their closest structural relative in Asia. This rapidly evolving minisatellite can therefore serve as a lineage marker for exploring recent events in human population history and dissecting population structure at the fine-scale level, as well as being an extremely informative DNA marker for personal identification. we then examined third degree relatives from two groups of siblings … More using two hypervariable minisatellite loci. Relationships were not established because no alleles were shared between the two groups ; albeit sharing of alleles within each group was noted in moderation. We also estimated the distribution of LRs in a variety of kinships (parent-child, siblings, two s! iblings etc.) using a commercially available typing kit which simultaneously amplifies 15 STR loci. Although the STR system is extremely useful in establishing individual identification when both parents, or two or more children (or siblings) are available for comparison it is highly unlikely that the system will be effective in third degree kinship analyses. This postulation is based on our study of samples obtained from known third degree relatives in which we attempted a microsatellite-based approach to establishing kinship. However, unfortunately with microsatellites alone the calculated LR was less than 1, which is insufficient for positive identification. Consequently, a more effective method such that estimates the proportion of chromosomal sharing would be more advantageous in comparison to attempting to demonstrate allelic hypervariability at several loci. To date we have analyzed 382 dinucleotide loci distributed throughout the human genome in order to estimate the length proportion of shared haplotypes between two individuals in varying modes of kinship. The initial data we have obtained is promising and is currently being carefully analyzed. Less