Genetic testing: Getting the DNA

Researchers can use DNA samples to find genetic combinations that might increase the risk of getting a particular disease. The DNA is often collected from the white blood cells in a blood sample. About 10 ml of blood is collected from patients involved in the study. They patients know that DNA studies are going to be done, and have given their permission to the researchers. It is important that the blood samples are 'anonymised', or coded. The laboratory number and person's name is kept in a database - this is so that the researchers don't lose track of the original identity of the samples. The blood is also divided into at least two samples so that some of it can be stored in a separate place to provide original material in case test results show up something interesting that needs to be checked.

Dr Andrew Shelling ( Faculty of Medical and Health Sciences, The University of Auckland Blood to us is still probably the best way of getting hold of genetic material, or DNA. Within the blood even though its red, we are looking for the white blood cells, which contain the DNA [The DNA in red blood cells breaks down as the cells mature]. It’s very important that we don’t lose track or lose identity of the samples. We often have multiple samples as well. We’ll take an aliquot out and store it in a separate place, just so that if we do find something interesting, we’ve got a sample to go back to just to confirm that everything’s A-okay.