A improved method for extracting genomic DNA from reserved blood

Objective To explore the modified potassium iodide method (Improved method) for extracting the long-term cryopreservation of peripheral blood genomic DNA. Methods The potassium iodide (KI) method was improved by increasing the blood volume from 100μL to 200μL, replacing the sterile distilled water with 0.9% NH 4 CL solution for destruction the red blood cells, increasing the 5 mol/L KI solution dosage(70μL) for cracking the white cells membrane, and centrifuging at low temperature(4℃ ). The modified potassium iodide method was used for extracting the genomic DNA from 82 blood samples reserved in -80℃ , and the concentration and purity of the extracted DNA was compared with the KI method. Meanwhile the extracted DNA was used as the template to amplify CYP2C19 gene by PCR. Results The extracted DNA concentration and A 260 /A 280 of the KI method and the improved method were 128.2±34.9μg/mL, 1.74±0.08 and 220±91.29μg/mL, 1.87±0.12, respectively. The DNA purity of improved method was higher, and there were significant statistically different (P0.01). The amount of DNA extracted by the modified method was more than that of KI method. The genomic DNA extracted by improved method were amplified using PCR, which result were stable. Conclusion The genomic DNA extracted from the long-term cryopreservation of peripheral blood using improved KI method had higher quality, which were able to meet the demand on the clinical study of cryopreserved samples.