Reading your DNA fortune

by Margo White / 04 December, 2012
Bespoke DNA testing to foretell your health future can be fraught.
Reading your DNA fortune
Getty Images/Listener photo illustration


'A little bit of spit is all it takes to start your journey,” says the website of the personal genome service 23andMe. Just send your saliva to them or one of several other DNA-analysis services around the world and you, too, can use your genome to explore your ancestry and discover what talents run in the family and what diseases you might be genetically predisposed to. But will getting your genome mapped be useful for your future health, or is it more like dabbling in fortune-telling?

Scientists have learnt a lot about the human genome in a very short time and the study of genomics is already influencing medical treatment both in clinical practice and in scientific research – providing insights into how a tumour might develop, helping doctors identify which cancer patients are more likely to respond to certain therapies and helping specialists refine a diagnosis or prognosis. Yet if it’s easier (and cheaper) to get your personal genome sequenced, interpreting the results is as complex as ever.

“It’s a rapidly evolving field, but right now, we don’t know how much weight to put on many findings,” says Cris Print, an associate professor in molecular medicine at the University of Auckland and co-director of the New Zealand Bioinformatics Institute. “If you get a result back from a direct-to-consumer test, you might go to the scientific literature and … look up associations between a particular gene sequence and a particular disease [to see] how likely it is that you’ll get it. But sometimes you’ll find quite conflicting results, like two research studies showing different things in different populations. Even an expert struggles to interpret that.”

Scientists now know that whether an inherited trait is manifested in an individual is not due to genes alone, but myriad other factors, such as diet, exercise, what diseases were contracted as a child, even dumb luck. Complicating matters are other genetic factors that invariably come into play. “We might find a mutation in a cancer patient and think, ‘Ah, this is the cause.’ But then we find that normal healthy people have the same variation but are disease-free, because other genes have taken over,” says Print.

In fact, the more scientists find out about the human genome, the more they find out how much they don’t know. For instance, much genetic science (and most genetic testing) has focused on 1% or 2% of DNA – the genes that encode for the proteins that make the building blocks in our body. Until about 15 years ago, the rest was thought of as “junk DNA”. Then it became apparent these other parts of the DNA, the “in-between genes”, have a significant role.

As scientists working on the ENDCODE (Encyclopaedia of DNA Elements) Project have shown, a genome is not just a collection of genes, but a complex system of genes and all sorts of regulatory mechanisms. For instance, in addition to our 30,000-odd genes are another four million-odd gene switches.

“In the past six months our world has been blown open,” says Print. “We’ve suddenly been faced with a huge increase in complexity over what we expected, in the way the genetic wiring in our cells works.” What Print calls a “tsunami of information” is revealing a lot scientifically, but it’s also making it apparent how difficult it is to translate that information into clinical practice. It’s daunting, but exciting. “The reason that some tests haven’t been that strong in the predictions they can make about disease or how well we will respond to a drug may be that we’ve just not understood how complex the system is. When we do, we’ll be able to make better predictions.”

In the interim, getting your genome mapped could be fun. “We all want information about our ancestry or whether there’s a predisposition to being good at something,” says Print. But it could also be fraught: how much do you really want to know? “Some people could get worried by the results. I suspect that it depends on who you are, and your expectations.” Either way, the future will still remain uncertain.

Health briefs


SLEEP-DRUG DANGER


A drug prescribed to help patients sleep in hospitals has been linked to an increased risk of falls, according to a study published by specialists at the Mayo Clinic in the US. They found the fall rate among patients who took Zolpidem during their hospital stay was more than four times as high as for those who didn’t, and that risks posed by the drug were greater than the risks associated with age, cognitive impairment, delirium or insomnia.

MIND YOUR HEAD


Research led by Professor Valery Feigin at AUT University and published in Lancet has estimated there are more than 36,000 new traumatic brain injuries (TBIs) in New Zealand each year. “This means one new TBI happens every 15 minutes, far more than the number of new heart attacks and greater than five times the number of new strokes,” says Professor Feigin. The rate is far greater than expected and strategies are urgently needed to reverse the “silent epidemic”. The population-based study is the first of its kind globally.

INSIDE EINSTEIN’S BRAIN


A “road map” to Albert Einstein’s brain has been published, appropriately, in Brain, in which researchers describe the father of relativity’s cerebral cortex from an examination of 14 recently found photo graphs. Although the size and asymmetry of Einstein’s brain weren’t unusual, other features definitely were, such as the “extra convoluted” parts of his prefrontal lobe, and “extraordinarily asymmetrical” parts of his parietal lobes.
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