Background

Allele frequency using short tandem repeats (STRs) is used to calculate likelihood ratio for database match, to interpret DNA mixture and to estimate ethnic groups in forensic genetics. In Korea, three population studies for 23 STR loci have been conducted with different sample size for forensic purposes.

Objective

We performed comparative analysis to determine how the difference of sample size affects the allele frequency and allele variation within same ethnic population (i.e. Korean). Furthermore, this study was conducted to check how the sampling group and multiplex kit also affect allele variation such as rare alleles and population specific alleles.

Methods

To compare allele variation, we used allele frequencies of three population data published from three Korean forensic research groups. Allele frequencies were calculated using different sample sizes and multiplex kits: 526, 1000, and 2000 individuals, respectively.

Results

The results showed the different distribution of allele frequencies in some loci. There was also a difference in the number of rare alleles observed by the sample size and sampling bias. In particular, an allele of 9.1 in the D2S441 locus was not observed in population study with 526 individuals due to multiplex kits.

Conclusion

Because the allele frequencies play an important role in forensic genetics, even if the samples are derived from the same population, it is important to consider the effects of sample size, sampling bias, and selection of multiplex kits in population studies.

中文翻译：

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根据韩国人群样本量使用等位基因频率比较分析等位基因变异

背景

使用短串联重复 (STR) 的等位基因频率用于计算数据库匹配的似然比、解释 DNA 混合物和估计法医遗传学中的种族群体。在韩国，出于法医目的，针对 23 个 STR 基因座进行了三项人口研究，样本量不同。

客观的

我们进行了比较分析，以确定样本量的差异如何影响同一种族人群（即韩国人）内的等位基因频率和等位基因变异。此外，本研究旨在检查采样组和多重试剂盒如何影响等位基因变异，例如稀有等位基因和群体特异性等位基因。

方法

为了比较等位基因变异，我们使用了三个韩国法医研究小组公布的三个人口数据的等位基因频率。使用不同的样本大小和多重试剂盒计算等位基因频率：分别为 526、1000 和 2000 个个体。

结果

结果显示在某些位点等位基因频率分布不同。样本量和抽样偏差观察到的稀有等位基因数量也存在差异。特别是，由于多重试剂盒，在 526 名个体的群体研究中未观察到 D2S441 基因座中的 9.1 等位基因。

结论

由于等位基因频率在法医遗传学中起着重要作用，即使样本来自同一群体，在群体研究中考虑样本大小、抽样偏差和多重试剂盒选择的影响也很重要。