Shelf life of whole blood samples in a biobank and the yield of deoxyribonucleic acid during genetic testing

Abstract

Aim. To study the effect of the shelf life of frozen whole blood samples in a biobank on the amount of released deoxyribonucleic acid (DNA).Material and methods. The study included whole blood samples placed in tubes with the anticoagulant EDTA (ethylenediaminetetraacetic acid at a concentration of 1,8 mg/ml) from participants in the epidemiological study ESSE-RF-1 and ESSE-RF-2 and cohort studies conducted at the National Medical Research Center for Therapy and Preventive Medicine. The samples were stored in the biobank of the National Medical Research Center for Therapy and Preventive Medicine at temperature from -22О C to -32О C. The shelf life from blood collection to DNA extraction ranged from several weeks to 11 years. DNA was extracted using QIAamp DNA Blood Mini Kit (250) and 96 Blood Kit (Qiagen, Germany). Statistical analysis was performed using the R 3.6.1 software. To analyze the association of blood storage time with the logarithm of DNA concentration, a linear regression was used.Results. The analysis included data on the DNA concentration of 5405 samples. Multivariate regression showed that the blood shelf life was significantly associated with a decrease in concentration by 3,92% (3,16-4,68) for each year of storage (p <0,0001). For 509 samples, the DNA concentration was measured twice, immediately after isolation and after 4,5 years of DNA storage at -32О C. During storage, the concentration of DNA increased by an average of 2% (p=0,046).Conclusion. Long-term storage of whole blood samples at temperature from -22О C to -32О C is associated with a decrease in the DNA yield. Long-term storage of the isolated DNA at a temperature of -32О C is not associated with a decrease in its concentration.