We can now edit genes in human embryos. Are we ready for custom babies?

Earlier this week, hundreds of scientists gathered in Washington DC for a 3-day summit. The purpose? To evolve a general consensus on genetic editing, an advancement that is likely to change the world in ways we simply cannot imagine.

What exactly is it?

Genetic engineering works by identifying and targeting specific sequences of DNA and using enzymes to snip it out of the genetic sequence. With the help of the cell's natural DNA-repairing ability, the technology then stitches the DNA back together.

Since gene-splicing became a reality a few decades ago, scientists have tried to identify disease-causing genes in the hope of deactivating them. The problem was that up until very recently, the techniques involved in genetic manipulation were prohibitively expensive.

However, a new advancement in gene-editing techniques called Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) has changed that forever.

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The technique uses an enzyme called CaS9 guided by an RNA molecule to target the desired DNA sequence and then disrupt, deactivate or insert the desired sequences. For a process that sounds that complicated it is a ridiculously cheap, easy and efficient one.

How cheap? Take, for example, a previous technique like the one used on the child with cancer - that required an enzyme called the zinc-finger nuclease (ZFN). Zinc fingers cost close to UD $5,000 and are difficult to engineer.

CRISPR on the other hand costs closer to US $30.

This reduction in cost has caused an explosion in the prevalence of genetic engineering, effectively democratising the field.

Sounds fantastic. What's the problem, then?

It took just under 100 years from the discovery of DNA to the moment James Watson and Francis Crick discovered its structure.

Fast forward 60-odd years and genetics has moved beyond anything its pioneers could probably have imagined.

We're now able to manipulate genetic information in incredible ways. Thanks to pioneering gene therapy, for instance, a young cancer patient is currently in remission. Another biotech startup has claimed to have carried out gene therapy to reverse ageing.

But it has also opened up a virtual minefield of ethical issues.

Where do we draw the line? Is it hubris to try and alter genes that evolution has selected over millenia? Should we tinker with the genome of embryos who have no say in the choice but will live with the consequences for life? Are we playing God by tinkering with genes?

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The problem is compounded by the fact that different countries have different laws and understanding of where to draw the line - especially when it comes to human beings. Perhaps it's natural for a field of science with near-limitless applications that each country picks its priorities to correlate with its prime concerns. But the fallout of that is that as a species, we may soon lose control of our own future.

Earlier this year, Chinese scientists caused a stir when they announced they had, for the first time ever, genetically modified human embryos. This in a country where genetic modification of human embryos is forbidden by law.

It's advances like this that lead to an urgent need for the Washington summit, especially in a time of increased access to gene-editing technology.

Unresolved issues

Thanks to the dramatic reduction in costs, genetic editing has been truly democratised.

But as in the real world, democracy has its own price.

Following China's experiment on human embryos, several genetic engineering experts have been speaking out, asking for a halt to all "germline engineering" (engineering embryos).

They argue that attempts to create genetically-engineered babies will result in a fallout far beyond our immediate understanding, and trigger a public backlash against all genetic research.

That's a risk they don't want to take again - back in 2000, genetic engineering was put on the backburner because of the highly-publicised death of a patient whose immune system reacted badly to the viruses involved in the technique.

While the technology has improved manifold since, the research community knows it cannot afford another public backlash.

Some of the work being done using gene therapy is path-breaking, possibly offering solutions to things such as Alzheimer's, cancer, HIV and muscular dystrophy. The general consensus on these is largely positive.

However, germline engineering threatens to put all of that at risk with both its technical and ethical implications. Experts have argued that not enough is known about the technology yet. Some argue that the approach to it has been to forge ahead because it works - rather than understand exactly how it works.

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As a result, the long-term implications and possible safety concerns surrounding it aren't fully known yet. Not enough for testing on humans anyway.

In the Chinese experiments themselves, researchers were only successful on "a fraction" of the 86 embryos involved in the experiment. More worryingly, they found that in a large number of cases the CRISPR had missed the target.

This is doubly worrying - it's not so much a mistake as a catastrophe. Not only would it fail to cure existing conditions, it could trigger a whole new set of problems.

In addition, studies have shown that genetic modifications at one spot may cause mutations in another, opening up a whole new can of worms.

But the technical considerations possibly pale before the ethical ones. While informed consent is possible with gene therapy, germline therapy involves permanently altering the genes of a person without their consent. Not only will the person have to live with altered genes forever, future generations would also inherit them.

And because our understanding of the long-term consequences is necessarily blinkered, it poses a massive responsibility to question every step we take. On the one hand is the reality that all scientific progress - from guns to nuclear energy - have the power to be misused. Biological warfare, for instance, is one such example.

Yet, limiting science because of its potential misuse would have meant our modern world would look nothing like it does today.

In genetic terms, this conundrum leads to a different question: evolution has gotten us to this point over millions of years; are we confident that the knowledge we've gained in the last 100 is enough to supercede evolution?

However, some scientists argue that the knowledge of the human genome to be gained by carrying out this research is too important to be ignored. Is that the majority consensus though? We'll know when the Summit's report comes out in 2016.

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