以STR基因進行手足關係鑑定的可靠性分析

The Reliability of Sibship Test Using STR Loci

10.6134/tjfm.2010.0202.06

林彥仰(Yen-Yang Lin)；李俊億(James Chun-I Lee)

DNA鑑定 ； 親子鑑定 ； 手足鑑定 ； STR基因 ； 似然比 ； 虛擬族群 ； Forensic DNA analysis ； Parentage testing ； Sibship testing ； STR locus ； Likelihood ratio ； Simulated population

台灣法醫學誌

2卷2期（2010 / 12 / 01）

34 - 41

繁體中文

親屬關係鑑定在現今人身鑑定中占有非常重要的地位，除了親子關係之外，手足關係算是其中相當重要的一項。本研究利用台灣地區3,794位漢人之15個STR基因頻率作為標準數據，以Excel函數建立3,500個三代完整的含STR基因型家族個體虛擬族群，從此族群中選取10,500組二人組和10,000組三人組手足配對作為具有親屬關係的相關組配對基礎，再隨機形成10,500組二人和10,000組三人的配對，作為不具親屬關係的非相關組配對基礎。計算這些手足配對的累積似然比，得出有親屬關係與無親屬關係的累積似然比分布狀況，分析得到敏感度、特異度和正確度等數據，結果顯示此二人組手足關係分析法在分析15個STR基因下，特異度達0.9999時正確度約為0.9047，分析12個STR基因，特異度達0.9999時正確度約為0.8599，若只分析10個STR基因，則特異度達到0.9999時正確度約為0.8210，此結果顯示二人組手足關係鑑定，增加分析基因數量，可以有效增加鑑定的可信度。進一步分析三人手足15個STR基因配對之似然比，結果顯示在相關組中，累積似然比均大於0，而非相關組有98.91%累積似然比為0，即排除率為98.91%，若判斷標準訂在累積似然比為0，則特異度為0.9891，敏感度為1，正確度為0.9946，此結果顯示三人組手足關係鑑定法，可以直接排除絕大部分非相關組配對，增加手足鑑定配對的人數可以非常有效的增加鑑定的可信度，達到極高的正確度，效果較增加分析的基因數量更為顯著。

The kinship determination has its important role in human identification testing now. Apart from parentage testing, sibship testing is an another important issue. There were STR genotypes of 3,500 simulated families within 3 generations generated based on Taiwanese's population data using excel software functions. There were 10,500 two-person pairs and 10,000 three-person groups of sibship selected from simulated population to be the related group of sibship testing. On the other hand, we generated 10,500 two-person pairs and 10,000 three-person groups used as non-related group of sibship testing. Likelihood ratios of sibship testing were calculated in simulated population, and distributions of related and nonrelated groups were established. The results of sensitivity and specificity of sibship testing showed that while the specificity was 0.9999, the accuracy could be 0.9047 in two-persons sibship testing with 15 STR loci; and the accuracy decreased to 0.8599 or 0.8210 in the same testing with 12 or 10 STR genes. While testing more numbers of STR loci, it is more reliable in the determination of sibling relationship. For further analysis of three-persons sibship testing with 15 STR loci, the result showed that all cumulative likelihood ratios of related trio were greater than zero, but about 98.91% of cumulative likelihood ratios with non-related trio were zero. The exclusion rate of three-persons sibship testing was 98.91%. If the threshold was greater than zero, the sensitivity, specificity and accuracy were 1, 0.9891 and 0.9946, respectively. The result showed high accuracy and exclusion rate in three-persons sibship testing, and it also revealed higher confidence level in the sibship testing of three-persons than two-persons. The effect of increasing numbers of STR loci was lower than increasing numbers of person in sibship testing.

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