粒線體DNA甲基化在法醫檢體年齡預測之研究

法醫研究所每年約有400件無名屍案件，大多為死者年齡不詳，一般而言死者年齡需依靠法醫師經驗及體質人類學等專家進行年齡估計，但這些專家可能存有主觀意見，難以數據化。因此本研究利用DNA甲基化分析結果，提供檢方及法醫師一項客觀的數據，進行年齡推估。本研究分析53件法醫檢體，年齡分布於20～97歲之間，區分成4個群組，分別為：20～40歲（20件）、41～60歲（14件）、61～80歲（12件）、81～100歲（7件）。分析每一檢體之粒線體鹼基位點，並計算p值，觀察粒線體DNA在不同位點甲基化情形，並篩選各年齡層具有顯著差異的粒線體位點，且R^2>0.1，各年齡層篩選決定係數較高的前3個位點來推估年齡，以迴歸線方程式分別計算各年齡層之預測年齡，研究結果顯示：20～40歲年齡層以粒線體3532、4441及11519位點計算，預測年齡平均值與實驗年齡差距區間為+5至-9歲；41～60歲年齡層以粒線體3592、4975及14280位點計算，預測年齡與實驗年齡差距區間為為+5至-4歲；61～80歲年齡層以粒線體547、4482及14280位點計算，預測年齡與實驗年齡差距區間為+5至-7歲；81～100歲年齡層：以粒線體3886、8951及11519位點計算，預測年齡與實驗年齡差距區間為+3至-4歲。在無名屍案件中，可比對尋親家屬所提供之失蹤者相關年齡資訊，透過年齡比對，輔助親緣關係計算結果，幫助失蹤者找到回家的路。因此，未來希望藉由此方法，深入探討更多案件，得到更精確的分析結果，提供檢察機關及法醫師進行年齡估計之參考。

關鍵字

粒線體DNA ；年齡預測；次世代定序；無名屍身分鑑定

並列摘要

Our institute has received about 400 unidentified bodies per year. Most unidentified bodies cannot be confirmed the age. In general, the forensic medical examiner and physical anthropological experts estimated the age of unidentified bodies based on their experience, but the results were difficult to quantize. Therefore, the purpose of our study hope to establish the method using results of DNA methylation to provide information for the forensic medical examiners to estimate age. Our research results showed that 53 forensic samples were divided into four groups based on the age: 20 cases for 20-40 years old, 14 cases for 41-60 years old, 12 cases for 61-80 years old, and 7 cases for 81-100 years old. We selected significant sites of mitochondrial DNA and calculated the methylation degree of each site. In addition, we selected top three significant site which the coefficient of determination was R^2 > 0.1 to calculate the predictably age of sample by regression line equations of the methylation degree of each site. The results indicated that the difference between the chronological age and the predictably age of 20-40 age group based on 3532, 4441, and 11519 sites is +5 and -9 years old. The difference between the chronological age and the predictably age of 41-60 age group based on 3592, 4975, and 14280 sites is +5 and -4 years old. The difference between the chronological age and the predictably age of 61-80 age group based on 547, 4482, and 14280 sites is +5 and -7 years old. The difference between the chronological age and the predictably age of 81-100 age group based on 3886, 8951, and 11519 sites is +3 and -4 years old. The predictably age of samples can assist unidentified bodies or missing persons to compare the kinship between relatives. In the future, we hope that this method can be utilized to provide more information and analysis more cases. This method can provide references for the procurator and forensic medical examiners to predict the age of forensic samples.

並列關鍵字

Mitochondrial DNA ； Age Prediction ； Next-Generation Sequencing ； Unidentified Bodies Identification

參考文獻

Dias HC, Corte-Real F, Cunha E, Manco L: DNA methylation age estimation from human bone and teeth. Aust J Forensic Sci 2020;54:163-76. doi:10.1080/00450618.2020.1805011

Hong SR, Jung SE, Lee EH, Shin KJ, Yang WI, Lee HY: DNA methylation-based age prediction from saliva: high age predictability by combination of 7 CpG markers. Forensic Sci Int Genet 2017;29:118-25. doi:10.1016/j.fsigen.2017.04.006

Dias HC, Cordeiro C, Corte Real F, Cunha E, Manco L: Age estimation based on DNA methylation using blood samples from deceased individuals. J Forensic Sci 2020;65:465-70. doi:10.1111/1556-4029.14185

Dias HC, Cordeiro C, Pereira J, et al.: DNA methylation age estimation in blood samples of living and deceased individuals using a multiplex SNaPshot assay. Forensic Sci Int 2020;311:110267. doi:10.1016/j.forsciint.2020.110267

Maulani C, Auerkari EI: Age estimation using DNA methylation technique in forensics: a systematic review. Egypt J Forensic Sci 2020;10:38. doi:10.1186/s41935-020-00214-2

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