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Unique Urine Fingerprints

This post was chosen as an Editor's Selection for ResearchBlogging.orgFor decades, the word “fingerprint” has been used to denote a set of unique characteristics, whether literally the complex patterns of arches, loops, and whorls on one’s fingertips or entirely figuratively and more recently, the notion of a genetic fingerprint based on an analysis of an individual’s DNA sequence.

Most recently though, scientists have turned to another “omic” metabonomic fingerprinting using the analytical technique of NMR spectroscopy to obtain a unique view of an individual based on the complete range of metabolites produced by their body.

In the press release that discussed the research and in my follow-up news story on Spectroscopynow.com, there was an allusion to the idea that each one of the 6.7 billion people on earth would have a unique metabonomic fingerprint.

Such an identifier might have forensic, biometric, and medical diagnostics implications for us all. But, at the time of writing, I was curious as to how the team could possibly assert that every one of us would be unique, given that only a handful of volunteers had been screened. So, I asked team member Ivano Bertini to tell me a little more about how this might work.

“How can one extrapolate from a few tens of individuals that all 7 billion people on earth can each have a unique metabolic NMR fingerprint. The answer is of course that one cannot be sure!” he told me.

“We hinted at this possibility because it is a legitimate extrapolation to make,” he adds, “I can offer you some speculation along these lines. The proton NMR spectrum of the urine of any individual contains a large number of signals, and the spectrum is usually divided into a few hundreds of buckets (or bins). Let us say 400 of them contain signals. The height of the bin is proportional to the intensity of the signal(s) contained in it. If you simply allow each of these bins to assume two height values, individuals can be characterized by 2400 different ‘states’ of their bins, an astronomical number! Even if you allow for several bins being correlated because they contain different signals from the same metabolite, and assume an average of 4 bins reflecting the same metabolite, you only go down to 2100, still an astronomical number. If some metabolites change their amount in a correlated way this number can go down further, but keep in mind that the population on earth is less than 233!”

So, it does indeed look like each of us would be entirely metabolically unique. But, even if that turned out not to be the case and there were only a few hundred, or a few thousand, unique metabolic NMR fingerprints in the whole human population this would still be very useful to know.

“Think of how important it has been to identify a handful of blood types,” Bertini suggests, “Having a baseline metabolic profile for an individual would allow us to monitor changes due to the onset of a disease (early diagnosis) or the effect of a drug treatment and so have an early prediction of the response to a treatment.”

We all like to feel that we are unique, even twins have different actual fingerprints, it’s interesting to think that this may reach all the way down to the contents of your bladder.

Research Blogging IconBernini, P., Bertini, I., Luchinat, C., Nepi, S., Saccenti, E., Schäfer, H., Schütz, B., Spraul, M., & Tenori, L. (2009). Individual Human Phenotypes in Metabolic Space and Time Journal of Proteome Research DOI: 10.1021/pr900344m

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