Transcripts of the Attorney General's Initiative on DNA Laboratory Backlogs (AGID-LAB) Working Group

Monday, October 21, 2002

THE MARSHAL CASSETTE

MR. VAN NIEKERK: The Marshal cassette, as I mentioned earlier, is a device that we have designed to facilitate the automation of blood samples in a forensic environment. We basically came up with this design to save on costs, to be very blunt about this. FTA is not a cheap way of collecting blood, transporting, and presenting blood, so we needed to basically cut down on the consumption of FTA paper, and I think much to the dismay of Wattman Belsi in the United Kingdom, we are using much less FTA paper per sample collection than they would like to sell to us.

Why do we use FTA? Just as a quick reminder, it is a simple and safe handling medium for genetic material as far as the collection, transport, processing, and storage is concerned. The benefits of this Marshal cassette that I've shown you - and I'll explain later on exactly how we go about using this - it provides us with a single solution for the collection, safe transportation, preservation, and automated processing of genetic material. As far as the automated processing is concerned, the DNA purification and sample isolation procedure just takes place in an automated fashion in the lab because of FTA and what it is.

The cassette that I've just shown you - and maybe I should go back to that slide just so that you have it in the background - you will see there a couple of holes, and I'm just going to point to those sitting down like this. Those holes over there are basically fitted with single disks of FTA paper.

What we do is we have a surgeon or medical practitioner draw blood from the person - and I'll explain the issue of blood later on - we have a medical practitioner draw blood from a person, and then the blood is spotted at the time of collection on the FTA paper. In other words, this means that it doesn't matter when we receive the sample in for analysis. The quality and quantity of DNA is within acceptable variances for us to be able to put it into an automated system.

I told that you we needed to save on cost, and the cost of this device, this Marshal cassette, works out to be the equivalent of about 50 American cents with the added cost of about $1 for the purification reagent that is required given the fact that we handle this cassette in an automated liquid handler, so this works out to be the equivalent of about six local telephone calls for the processing of a sample.

The beauty of this is that we don't need any lab technician intervention. Given the fact that we receive the sample already spotted - or the blood sample already spotted on FTA paper, we don't need a lab technician to sit down, take a sample, spot it onto FTA paper, allow it to become dry, and the whole process that goes with that. Another bonus is the fact that we don't need to quantify the DNA. Given the fact that a specific size of disk is punched out from the cassette into a PCR tube rack, we just don't need to quantify the DNA, and that adds to time saving, to cost saving.

This just gives you a basic indication of the components of the kit that is required for the collection of blood for spotting onto the Marshal cassette. This device that you see over there is something that is being used quite extensively or that used to be used quite extensively in hematology labs for making blood smears. It's called a Diffsafe. That's the trade name.

Basically what you will do is, as you will see later on, what you want to do is spot blood from the chip directly onto the FTA paper without removing the cap. So what is required is for a Diffsafe to be inserted through the closed stopper of the tube and then the tube is physically inverted and you press down on the tube, and a single droplet of blood is spotted onto the FTA paper where it becomes dry within a couple of minutes.

I think from our understanding this is basically what this whole meeting is all about and why we're so fortunate to be invited to be here. The improving of lab efficiencies is I think high on the agenda, if not at the top of the agenda, internationally at this stage given the fact that DNA is becoming the mainstay of forensic human identification through DNA typing.