13 Apr 2022

Cracking the final piece of the human genome puzzle

From The Detail, 5:00 am on 13 April 2022
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Output from a DNA sequencer. Photo: National Human Genome Research Institute

It's taken thousands of scientists decades to finish mapping the human genome. The Detail looks at why it's taken so long and what it might mean for indigenous populations here in Aotearoa and around the world.

The news that scientists have finally finished mapping all of the human genome appears to have slipped largely under the radar.

Possibly that's because most of us thought it had already been done, 20 years ago. But it had only been mostly done – and it's taken two decades to crack the last eight percent.  

Accelerated technology has meant the last bit of information has come in a rush. Filling in the pieces of the puzzle has also shown scientists those last, scrappy bits were more important than was first thought.  

"When we start to look really carefully by taking human genomes that we've already analysed, we're finding that we've made lots of mistakes previously, without knowing about this last eight percent," says Professor Cris Print, from the University of Auckland's Department of Molecular Medicine and Pathology.  

Print tells The Detail about filling in the missing pieces of a puzzle that have taken decades, thousands of scientists and billions of dollars to find.  

"We're around 40 percent the same as a banana, genetically," he says. "Yet we are so, so, so different.  

"Around one in a thousand of our individual parts of our genomes are different from other humans, and those one in a thousand obviously bring massive differences, but also there’s that huge similarity between us." 

Print has had his own DNA sequenced and says it's transformed him in a way. It identified a particular vulnerability to blood clots. Measures he's taking to prevent them - special stockings on planes, taking aspirin – have probably given him a few extra years of life.  

He says mapping your own DNA sequence will lead to precision healthcare, when it comes to targeting medicine to the particular type of issue you have. 

But he says there are ethical issues we need to address, including the mapping of infants at birth, and how we map the genomes of diverse peoples around the world.  

Print says New Zealand is leading the world when it comes to indigenous genome work.  

The Aotearoa New Zealand genomic variome project aims to obtain a full picture of DNA sequence variation within te ao Māori, that would be used as a diagnostic resource.  

At the moment most DNA mapping is of European or increasingly Han Chinese populations, with limited applicability to Māori and Pacific populations here.  

Associate Professor Phil Wilcox, from the Department of Mathematics and Statistics at Otago University, tells The Detail the project is working with other indigenous researchers in Australia, the United States and Canada, to make sure the science is appropriately applied and communities get the benefits from that work.  

"In our lifetime DNA sequencing will become a routine diagnostic tool," he says.  

"Right now when a child is born there's a heel prick done, the blood is blotted onto a Guthrie card, that card is sent away and analysed for [tens of] metabolic conditions. DNA sequencing will probably replace that.  

"There's information on five thousand conditions housed in a genome, so this is around the corner." 

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