Isolation and storage of DNA for population studies

For genetic population studies, human genomic DNA is commonly isolated from peripheral blood. A fast, non-invasive DNA sampling method is developed involving oral samples taken with cotton swabs. In addition various procedures were compared for isolation of DNA from different sources: whole blood or buffy-coats stored at −20°C for 5–10 years or buccal cells collected freshly with the non-invasive method. The differences in these procedures, which do not contain a phenol-extraction, are based on the use of either 1) high concentration ammonium acetate followed by DNA precipitation or 2) high concentration potassium acetate, followed by chloroform extraction and normal DNA precipitation.