Effects of blood storage time and temperature on DNA yield and quality

Whole blood is a common source of DNA, especially for genotype diagnostic services. Many laboratories now receive blood samples by mail and/or store blood samples prior to DNA extraction. Therefore, the effects of storage time (number of days from blood collection to DNA extraction) and temperature on DNA yield and quality are important. We compared DNA yield and quality from bovine blood samples exposed to one of sixteen treatment combinations of storage time (3, 7, 14 or 28 days) and temperature (-20 degrees, 4 degrees, 23 degrees or 37 degrees C) to the results obtained when DNA was extracted within 4 h of collection. The highest mean DNA yields, relative to the control samples, were obtained from blood stored at 4 degrees C. Blood stored at 37 degrees C for > or = 3 days or 23 degrees C for > or = 7 days yielded less (P < .05) DNA, compared with blood stored at 4 degrees or -20 degrees C for up to 28 days. DNA was not recovered from three of the samples stored at 23 degrees C and five of the samples stored at 37 degrees C. The genomic DNA obtained was of high molecular weight and suitable for restriction enzyme digestion and PCR amplification, regardless of the treatment.