Cheek cells are helping keep blood vessels open

How you respond to any medicine is dependent on your genes. This is why, some people get better when taking a particular medication, while the same medication, can make someone else very ill.

In the last few years, science has made a great deal of progress in figuring out which genes really count, when it comes to drug effects. But, doctors treating patients have not been able to apply this science to their patients on a routine basis.

So prescribing meds often ends up being a trial-an-error process, because having the lab work done, takes too long and genetic tests cost a fortune.

But things are changing……

Genetic tests are moving out the lab

The fancy name for genetic tests that happen at the bed side, instead of in the deep dark corridors of the lab, is a Point-of-care test.

The one that has finally made it into main stream medicine is called RAPID GENE. This is the first of many, and Point-of-care tests are likely to become a routine part of medical care.

The RAPID GENE test, is designed to help doctors choose which anti-platelet treatment is going to be the best option, when they’re working hard to clear out blocked pipes. Blocked pipes are typically a medical emergency, so there isn’t time to take a blood sample, run it up to the lab and wait a week or two for the result. The doc needs to make a decision in the moment.

So what does RAPID GENE test do ?

Quick as a flash, the test is able to analyze your DNA and look for what version of a particular enzyme you’re carrying.

The way it does this is to scrutinize the cells that are sloughed off from the lining of your mouth – after the test strip is rubbed against it. These lining cells are always being worn away – it is a pretty painless way to get a little piece of you, hallelujah – no needles !

The enzyme the test is interested in, is one of your cytochrome P450 enzymes. You actually have quite a collection of them and everyone’s collection is a little bit different. The cytochrome P450 enzymes are responsible for cleaning up the chemicals in your body – they are your official detox team.

The reason you have them, is primarily to clean up your body’s own chemicals, but they work just as well on foreign chemicals, whether of food origin or pharmacological. The enzymes systematically and efficiently slice and dice them, so they eventually end up in your pee and/or pooh.

Star 2 variant leads to a sticky situation

The enzyme the test is looking for is CYP2C19*2.

Don’t tune me out – all this means is, they’re looking to see if you have variant 2, of a cytochrome named 2C19. Remember I said, you have quite a few of these cytochromes – to keep things simple, they were never given proper names, instead scientists just identify them using numbers.

The CYP2C19 comes in several varieties – only one variety creates a sticky situation, when it is used alongside the anti-platelet medicine known as Plavix® – clopidogrel.

RAPID GENE prevents sticky situations

Clopidogrel works really well most of the time, but people who have variant 2, of the CYP2C19 break down the drug extremely quickly, so the drug ends up not doing its job, which is to keep the stent which is propping open the blood vessels – open.

If the stent blocks up – this is TROUBLE, with a capital T.

Researchers from University of Ottowa have shown, the RAPID GENE test is able to cut down on stent blockages, in a hospital setting. By identifying people for whom clopidogrel was not going to be effective, the sticky situation known as high on-treatment platelet reactivity (HPR), was completely eliminated, without this information, 30.4 % of patients end up suffering HPR.

Is this just another item they’ll be adding to the bill ?

As with most medical advances – the cost of the test is likely to be pricey. But, as the technology becomes more routinely available, the price will drop.

Pharmacogenomics is going to ultimately save money, because bad reactions to drugs end up being costly – sometimes the cost is a longer stay in hospital, due to complications, but some people pay with their lives.

NOTE : Tests like this one, provide information which is actionable, which makes it valuable, but be careful of spending a fortune being tested for some or other gene or combination of genes just for “fun”. The science is not ready to tell you what you can or cannot eat – the idea of DNA diets is largely hype, not science, because how you handle food, is the sum of hundreds of genes, not one or two. Plus, owning a gene is only half the story.

Point-of-care genetic testing for personalisation of antiplatelet treatment (RAPID GENE): a prospective, randomised, proof-of-concept trial. The Lancet (2012) 379 (9827):1705-1711. Jason D Roberts, George A Wells, Michel R Le May, Marino Labinaz, Chris Glover, Michael Froeschl, Alexander Dick, Jean-Francois Marquis, Edward O’Brien, Sandro Goncalves, Irena Druce, Alexandre Stewart, Michael H Gollob, Derek YF So.

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