DNA鑑定分析方法和群體遺傳學

DNA Profiling and Population Genetics

The successful application of DNA profiling in the Pitchfork case was a historic change in the investigation of crimes that assists the prosecution to exclude the innocent and convict the perpetrator of the crime. The rapid developments in DNA technology have not only had major implications for the identification of criminals in criminal investigations, but also have resulted in overall changes in the clarification of civil cases. This article reviewed the various methods of DNA profiling and the issues of the population genetics of Taiwanese (Hans), the foreign workers and the aboriginals in Taiwan. There are two main methods, RFLP and PCR-based methods, both all of which are derived from the characterisation of DNA polymorphism. RFLP method, genetic types at variable number of tandem repeat (VNTR) loci are determined and used to analyse human chromosome DNA. Now, various PCR-based methods, particularly STRs, are widely being used. Reviews of the research on the population genetics, Taiwanese showed no deviation from Hardy–Weinberg equilibrium. The foreign workers, Philippines and Thailand in Taiwan, also showed no deviation from Hardyand the issues of the population genetics of Taiwanese (Hans), the for Ami and Atayal) showed significant departures from genetic equilibrium. We suggest that if the race of the person who left the DNA sample is known, the database for the person‘s race should be applied; if the race is not known, calculations for all racial groups to which possible suspects belong should be made.

自從一九八六年傑佛瑞（Jeffreys）成功將 DNA 科學鑑識技術應用於英國 R v Pitchfork 犯罪刑案調查，DNA 鑑定已成為刑事犯罪專家利用生物學檢體偵測犯罪的一種新工具。在科學家日益求精的努力下，DNA 鑑定技術日趨成熟，此技術並已成為法醫學上極為重要的鑑識工具，同時在民事案件中，它也是對親子鑑定最有說服力之鑑識工具。本文回顧了各種 DNA 鑑定分析的方法和台灣人、本國外籍勞工、原住民之族群遺傳學議題。DNA 鑑定分析主要分為兩種鑑定方法，分別為限制性片段長度多型鑑定系統（RFLP）和聚合酶連鎖反應鑑定系統（PCR）的方法，這兩種方法皆基於 DNA 型別多樣性之特色而開發出來。RFLP方法用於分析人類染色體 DNA 特定位置重複序列之變異類型；聚合酶連鎖反應鑑定系統，特別是 STRs 方法，藉由 DNA 片段重複次數之相同或相異情形，辨識樣本檢體之同源性或其血緣遺傳關係，目前廣為刑事科學採用。我國族群遺傳學研究顯示，台灣人之基因型別頻率不偏離 Hardy–Weinberg 平衡，在台定居或工作之外籍勞工（菲律賓人和泰國人），基因型別頻率亦與台灣人相同，不偏離 Hardy–Weinberg 平衡。然而研究顯示，兩個臺灣原著民族（阿美族、泰雅族）卻明顯偏離遺傳平衡原則。本文建議，待鑑定之 DNA 樣本若已知來源屬哪一種族裔，則應以該族裔之族群資料庫基因型別計算，如果未能確定待鑑定之 DNA 樣本族裔，則應作出所有可能所屬的族群資料庫基因型別分別計算。