Skip to 0 minutes and 7 secondsMy name's Aamisha Kyada, and I'm an assistant genetic technologist in the genetics department. I'm going to show you how we extract DNA from a blood sample. The blood sample is in a tube containing EDTA to stop the blood from clotting in the tube. This is what the DNA looks like.

Skip to 0 minutes and 24 secondsWhen a blood sample arrives in the lab, we check that the patient's identifying details on the blood tube match those on the request form and then record the patient's name, date of birth, and NHS number on the lab database. A unique barcode is printed and stuck onto the blood tube so that we can track the sample through every stage of the testing process to ensure that the correct result is issued for that patient. We extract DNA from blood samples using an automated DNA extraction robot. The separation of DNA is achieved through capture onto magnetic beads, which are then attracted to metal rods magnetised by an electromagnet.

Skip to 0 minutes and 58 secondsThe magnetic rods transfer DNA bound magnetic beads through a series of different wash buffers. In the first step, the rods take up sheaths to prevent cross-contamination between the patient samples. The next step is to break open the cells to release the DNA that's located inside the white blood cells. We use a lysis buffer to break open the cells, and a protease enzyme to remove proteins from our blood samples. The magnetic rods are rotated to mix the solution. Magnetic beads and a binding solution are then added to the sample to bind the DNA. After binding, the electromagnet is switched on, and the DNA bound to the beads is attracted to the rods.

Skip to 1 minute and 37 secondsThe DNA undergoes a series of washes to remove any impurities and inhibitors that might affect the next stage of the genetic testing process. After removing the last traces of water buffer, the DNA bound bead pellet is resuspended in elution buffer to release the purified DNA from the beads. The last step is to transfer the DNA into your barcode-labeled tubes. Once we've measured the amount of DNA and checked that it meets our quality standards, we are ready to start the genetic test.

From blood to DNA

In this video, Amisha will tell you about the first stage of the laboratory process that leads to a genetic test result - DNA extraction from samples.

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This video is from the free online course:

Genomic Medicine: Transforming Patient Care in Diabetes

University of Exeter