（1. Department of Clinical Laboratory, Huadong Sanatorium, Wuxi Jiangsu 214065; 2. Department of Clinical Laboratory, Wuxi People′s Hospital Affiliated to Nanjing Medical University, Wuxi Jiangsu 214023, China)
Abstract：Objective: To evaluate the domestic kit of cellfree DNA(cfDNA) extraction from plasma. Methods: Plasma pool A was composed of volunteers plasma, and different length of DNAs were added into the plasma pool A to form the plasma pool B1-B4, the addition of DNA fragments length were 102, 268 and 402 bp and their mixture, respectively.The cfDNA in plasma pool A and pool B1-B4 were extracted by Qiagen and domestic column free DNA extraction kit. The extraction efficiencies of cfDNA in plasma pool A of two Extraction Kits were analyzed by Ct value of TaqMan qPCR, and the linear relationships between the extracted cfDNA concentrations of two Extraction Kits and the amount of plasma pool A were analyzed, and fragment size bias of cfDNA were analyzed by gel electrophoresis. The different DNA fragments recovery rates in the plasma pool B1-B4 of two Extraction Kits were determined by the nucleic acid analyzer. Results: The Ct values of cfDNA in plasma pool A extracted by Qiagen and domestic kits were 27.94±0.423 and 27.41±0.356, respectively, and the cfDNA extraction efficiency of domestic kit was obviously higher than Qiagen kit(t=4.29, P<0.01); There were a significant linear correlations between the cfDNA concentrations extracted by Qiagen and domestic Kit and the plasma pool A dosage, r2 were 0.979(P<0.01) and 0.963(P<0.01), respectively; Gel electrophoresis results showed that the cfDNA in plasma pool A extracted by the two methods appeared obvious bands at 102, 268 and 402 bp, and 1 204 bp fragments did not appear. The recovery rates of 102, 268， 402 bp and their mixture in the plasma pool B1-B4 extracted by Qiagen and domestic kits were 64.81%±4.27%, 80.40%±4.31%, 88.40%±6.11%, 83.50%±5.21% and 73.50%±5.33%, 85.20%±4.49%, 89.30%±5.91%, 85.64%±4.48%, respectively, and there were significant difference between two methods in the recovery rates of 102 bp and 268 bp DNA fragments(t=5.69,P<0.01;t=3.44,P<0.01), then there were no significant difference between two methods in the recovery rates of 402 bp and DNA mixture(t=0.47，P＞0.05; t=1.39，P＞0.05). Conclusion: Domestic cfDNA extraction kit can be comparable with Qiagen product in all evaluation parameters.
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2018, Vol. 28 
