中國人之粒線體控制區域 (D-loop) 鹼基序列多形性的探討

摘要: 粒線體DNA是細胞內獨立於核染色體外的DNA分子。相較於核染色體DNA，它具有母系遺傳，呈環狀結構，拷貝份數多，及變異性大等特點，很適合法醫刑案上個人身分鑑別時使用。過去的研究發現粒線體DNA在控制區，即D環上有較高的變異率，其中尤其是分布位置在核甘酸序列第16086到16399之間，和43到332之間的兩段具有異於平常的高變異頻率，分別稱為HVR-I及HVR-II。然而過去的研究大多侷限在這兩個區域，而且許多較早的研究是以限制酶多形性來區分型別。對這兩個變異區以外的D環其餘位置，雖然Lutz在1999年曾報告過另一高變異區HVR-III位在479到568之間，但是在這些變異區以外D環其餘的位置，及限制酶切斷位置以外的部分之核酸序列變異性仍值得作進一步探討。我們使用PCR放大及直接定序的方法研究63位沒有血緣關係的台灣地區漢人整個粒線體DNA控制區D環的基因鹼基序列，發現了127個位置具有DNA序列的多樣性，總計有788個變異型。在已報告過的三個高變異區中，HVR-I上有72個變異位置，HVR-II有35個位置，HVR-III有13個位置，而有9個位置是在上述三個高度變異區域之外，並有叢集在16465到16527間的現象，另外還發現33個未曾有文獻報告的位置出現DNA序列多樣性。比對結果其基因歧異度 (genetic diversity) 在HVR-I是0.999，HVR-II是0.993，HVR-III是0.850與過去文獻所得結果相仿。而16465到16527間新發現之高變異區基因歧異較低為0.614。而鑑別力則分別是0.983，0.977，0.837，及0.604。我們也發現19例的粒線體基因異質化現象，基因異質化出現在310位置，其形式為一胸腺嘧啶插入，此位置之基因異質化過去文獻中也有報告，我們的實驗發現310位置基因異質化出現的頻率約為30﹪而過去文獻報告則為13﹪。

關鍵字

粒線體控制區域 (D-loop) ；多形性；異質化；高變異頻率I ； II ； III

並列摘要

Abstract: Mitochondria DNA (mtDNA) is a subcellular sequestration. It is maternally inherited and exists in a high copy number in each cell in addition to rapidly evolving. The variable sites in the control region consists of two hypervariable segments, HVR-I and HVR-II. The sequence polymorphisms in control region between individuals are useful markers for personal identification in forensic application. Although a number of population genetics studies have already published, population genetic of the Chinese population, has not yet been established satisfactorily. We performed PCR amplification and direct sequencing to investigate the polymorphisms of the D-loop in mtDNA from sixty-three unrelated Chinese in Taiwan. Total 788 polymorphisms are found distributed in 127 variable sites. Seventy-two variable sites are in HVR-I region, thirty-five variable sites in HVR-II, and thirteen variable sites in the HVR-III, also nine sites in the regions outside the above HVRs. Thirty-three novel variable sites are not been described yet. The genetic diversity of HVR-I HVR-II and HVR-III are 0.999, 0.993, 0.850 respectively and 0.614 for and region outside the HVRs. The power of discrimination of the HVR-I HVR-II and HVR-III are 0.983, 0.977, 0.837 respectively, and 0.604 for the areas outside the HVRs. There are nineteen cases in the study found with heteroplasmy at sequence of 310, which show two populations of mitochondria; one with insertion of thymine, and the other without. High frequency of heteroplasmy at sequence 310 is quite different from the previous report.

並列關鍵字

mitochondrial control (D-loop) ； polymorphism ； heteroplasmy ； HVR-I ； II ； III

參考文獻

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中國人之粒線體控制區域 (D-loop) 鹼基序列多形性的探討

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