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Researchers map genome of unborn foetus

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Friday, June 08, 2012

US scientists have mapped the genome of an unborn foetus, marking a significant breakthrough in genetic medicine but also one that raises profound ethical issues.

As a result, researchers at the University of Washington say they will be able to screen a foetus that is only eight weeks old for thousands of genetic disorders with an accuracy of 98 per cent.

Currently, the common procedure for pregnant women who want to check their baby for chromosomal abnormalities, known as amniocentesis, is a risky procedure which involves a very big needle.

But researchers were able to map the genomes of two foetuses by taking small pieces of DNA from the unborn child which were present in the mother's blood stream.

Researcher Jacob Kitzman says in addition to sequencing those pieces of DNA, researchers were able to sequence each of the parents to pull together the genome sequence of the child.

"We think it's a huge improvement. Many genetic screens that are done today require an invasive procedure," he said.

And on the other hand there are non-invasive tests but those can only look for a handful of disorders.

"If you think of the genome as a book with multiple chapters, those current tests can detect if an entire chapter is missing or if there's an extra copy of an entire chapter.

"But what we've shown is that this can go down to the level of looking for a single typo."

There are more than 3,000 single gene disorders which this method may be able to detect, one day.

Mr Kitzman says proving it is possible to detect the multitude of gene disorders is the next step.

"If one had the full genome sequence of an unborn foetus, these disorders could be diagnosed comprehensively," he said.

"In the studies we had two families where the baby was born and apparently healthy. So this would need to be refined and replicated and shown that it can actually detect a disease.

"But in principle, as with other genome sequences approaches, this would be very much useful for that purpose."

Cutting edge

Professor Andrew Sinclair from the Murdoch Children's Research Institute in Melbourne says it is a significant advance but a clinical application is a long way off.

"This is right at the cutting edge. This is research but a lot of this research has translated quite quickly into the clinic so it'll be interesting to see how fast this does move into a clinical setting," he said.

Professor Sinclair says interpreting all the information made available by mapping the genome will be a challenge in itself.

"There's so much data there to look at. There's a lot of what we call variation in the DNA sequence - in the gene sequence - some of which is associated with pathologies and some of which is just variation that creates difference between individuals," he said.

"And currently we don't have enough information to necessarily distinguish between those.

"Some diseased genes we do and changes in them, we are familiar with that. But there's a lot of variation out there which is very grey so you're getting much more information, and potentially predictive information, about the likelihood of contracting diseases, which there's a lot that's not well worked out."

Ethical issues

The ability to map the genome of unborn babies raises all sorts of ethical issues.

Associate Professor Michael Selgelid, the director of the Centre for Human Bioethics at Monash University, says the first issue that comes to mind is "informed consent".

"So the information is revealed by such mapping could potentially benefit the person, the foetus or the newborn will develop into. But some of it could also end up harming the person that the newborn will develop into," he said.

"Well right now the human genome isn't all that well understood.

"So it could be discovered that there are certain genetic sequences that code for particular diseases. That may be diseases that are stigmatised or that might lead to discrimination of the people that have them.

"Certain genes might be statistically associated with certain diseases, and then if that's the case then people with those genetic sequences that may predispose them to certain diseases will be discriminated against, so maybe it will be harder for them to get jobs, maybe it'll be harder for them to get healthcare, life insurance and so on."

Source: Science Translational Medicine
2.0 from 3 votes
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