A reliable and effective method of DNA isolation from old human blood paper cards

Blood paper cards provide an effective DNA storage method. In this study, we used three DNA dissolving reagents (Tris-EDTA [TE] buffer, Tris-HCl buffer, and water) and one common commercially available kit (DN131 from MRC Inc) to elute DNA from 105 human blood paper cards collected up to 10 years ago. These DNA samples were used as templates for amplification of a single nucleotide polymorphism (SNP, C125T) region of human caspase-12 by PCR and a specific Taqman genotyping assay using the same amount of DNA. We show that DNA isolated by Tris-HCl buffer has higher yield and quality in comparison to DN131 solution. PCR success rate to amplify caspase-12 C125T SNP using Tris-HCl is comparable to the method using DN131 (89.5% vs 87.6%). The Taqman genotyping success rate using Tris-HCl is higher than using DN131 (81.9% vs 70.5%). Using TE or water, PCR success rates are lower than using DN131 (73.3% [TE]; 72.4% [H2O]), but Taqman genotyping success rates are comparable to the method using DN131 (70.5% [TE]; 79.1% [H2O]). We concluded that using Tris-HCl is a reliable and effective method to elute DNA from old human blood paper cards. The crude DNA isolated by Tris-HCl can be used to study genetic polymorphisms in human populations.