Saturday, 28 April 2012

Caught read-genomed

Here's me having a pop at writing about some actual science - yeah it does happen every now and then.

With the advent of cheap, high throughput sequencing it’s only a matter of time before we all have our personal genomes, all three billion base pairs of it, at our disposal. It’s fairly obvious how having our own genome sequenced can, and will, revolutionise medicine from personalised drug treatment to identification of a whole host of risk factors in disease. There are other far-reaching and seemingly far-fetched uses for our genomes though. One area that may see some of the biggest advances is in the world of forensics.

We’re all familiar with how DNA can be used to catch criminals, or identify otherwise unrecognisable bodies, but whole genome data may prove to be an even greater jump and could potentially make murder mysteries an impossibility. Imagine you have committed a crime and your DNA is found at the crime-scene. What would your chances of eluding the police be in post personal genome world?

With whole genome data, the likelihood of it being someone else’s DNA is minuscule. You’d literally have to have an (evil) identical twin on the loose if the DNA was a perfect match. 

Can you tell which one is the evil one?

 But being able to match someone’s DNA with certainty is only the tip of the chromosome in terms of what your genome can tell investigators.

You may think, as a first time criminal, your DNA won’t be on a database so you’re safe as they won’t know anything else about you.

Think again.

Formulae have been written that can predict your location of birth to within 23Km, in some cases, based solely off your DNA. This works due to the fact that geographical barriers restrict non-random mating from occurring.  For example, a woman on a small pacific island is far more likely to mate with a man on the same island than with a man who is at the top of Mount Everest.  This produces differences in allele frequency (an allele is a variation within a given gene or group of genes). By matching the allele frequencies with the frequencies observed in a given location, predictions can be made about your place of birth. Considering many people never stray that far from their place of birth it means police would have a good idea of where to look if your DNA was found at the scene of the crime. So without you even being on a database they can still track you down.

                My evil twin hopes to evade the fuzz by living 300 miles from his place of birth.

They might know where you are but it’s not like they know who to look for? 

Wrong again.

The genetics of facial features and morphology is being actively researched. We all tend to look a lot like one, or a mixture of, our parents and that’s because we have inherited their genes and some of those genes determine what we look like.  It’s still very early days in the field but imagine when (and in science it’s a case of “when” rather than “if”) they crack the genetic code of our appearance. They will be able to print out a photograph of what you look like with nothing more than your genome. Wigs and Sunglasses will become the criminal’s must have fashion accessories.

                                                 Incognito evil me

To cap it all off, that part I said about them not knowing who the DNA belongs to, if you’re not on a database already? It was a lie. They can work that out too. If you have any relatives with a criminal record they can tell whether you were at the scene of the crime based on your similarity to their genomes. For example; if you had a sibling with a criminal record your DNA would be a better match to them than a random member of public. The more family members you have with a criminal past, the easier it will be for them to know it was your DNA at the crime scene. But this all sounds like science fiction, such techniques must be years away? This technique has been used in the UK since 2008 and has already helped solve 20 crimes to date. The future is already here.

                    Chances are if you are related to these guys then the police will know who you are.

While this is all good news for the law abiding among us, and for those seeking justice, what hope is there for criminals and writers of crime dramas in the near future? Neither can always rely on “evil twins” or the possibility the criminal is a well travelled orphan with plastic surgery to stand a chance of evading the police. A time will come where they will know who you are, where you are, and what you look like based solely on your DNA. Criminals will literally become their own worst enemy in the form of their genomes. 

                      And I'd have gotten away with it if it wasn't for those pesky genome sequences...

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