Are scientists working on genetically modified babies?

Earlier this week a team of researchers in China announced the results of a study attempting to modify human embryos with the help of the cutting-edge gene-editing technique called CRISPR.

It’s the second time researchers have performed experiments sparking fierce ethical debate about genetically modifying human offspring.

So, here’s a simple breakdown of what you need to know about this research.

What is CRISPR?
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While genetic modification has been around for a few decades, CRISPR is the fastest, easiest and most accurate tool yet for snipping into DNA and removing, switching, or swapping out genes. Discovered in 2012, it has been heralded as a transformative technology that could radically change what humans are able to do in biology.

CRISPR - which stands for ‘clustered regularly interspaced short palindromic repeats’ - was discovered in bacteria as a natural defense mechanism from viruses. The method involves recognising the DNA of an invasive virus and using enzymes that can snip it, disabling the viral infection. Watch the video below from McGovern Institute for Brain Research at MIT for a simple explainer on how this technique has been adapted for use in the lab.

What are the uses of CRISPR in human gene editing?
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Even though scientists have been tinkering with genetics for decades, making highly specific changes in a particular gene quickly and efficiently wasn’t feasible until CRISPR came along. With this new tool researchers are able to tinker with genetic information much like you would when targeting and correcting spelling mistakes in a text.

This opens up the theoretical possibility that one could replace faulty genes in human embryos before they manage to develop a heritable disease - the ultimate genetic modification of a person.

Since all our cells carry our genetic information in the shape of DNA, such intervention could happen at the absolute earliest stages of conception, when the embryo consists of no more than a few germ cells.

Scientists given go-ahead to alter DNA of embryos using CRISPR
A British scientist has been granted a licence to edit genes of human embryos for research, a move some claim will lead the way to designer babies.

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What did the researchers try?
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To date only two studies have been published describing CRISPR technique used in actual human embryos. Both are the work of a research team from Guangzhou Medical University in China.

In the study published this week in the Journal of Assisted Reproduction and Genetics the team modified embryos to introduce a known genetic mutation that makes people immune to HIV. To do this, the researchers took 45 embryos at the earliest stage of development - only one cell - and injected them with the necessary CRISPR instructions.

Due to ethical concerns, such work could not be carried out in normal embryos. Therefore, just like in a study published last April, the researchers used human embryos rejected by IVF clinics as unviable due to an extra set of chromosomes. As you will see, this poses additional problems.

 

Did it work?
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The results so far haven’t been promising. Of the 45 one-cell embryos that received a CRISPR treatment only 26 made it past an eight-cell stage. Of those, only four actually carried the genetic mutation for HIV immunity.

“For ethical reasons, the embryos used were abnormal, and not likely ever to develop into a foetus if implanted in the uterus. That in itself raises the question of whether the outcome of the experiments has clinical relevance,” says Professor Bernie Tuch from NSW Stem Cell Network.”

Another problem the scientists face is inconsistency - once the edited embryos developed further, only some of the cells had the mutation, while others did not. Such a genetic mosaic of cells in one body would mean the person could still be vulnerable to HIV. If the introduced mutation was of another sort, the potential problems are hard to predict.

“Work on normal human embryos, focused on questions of basic human biology, is more likely to produce useful data,” says Dr Debra Mathews from Johns Hopkins Berman Institute of Bioethics.

 

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So are we going to have “designer babies”?
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Even though theoretically genetic modification of humans has been feasible for a few decades, it is only since the arrival of CRISPR that it’s becoming actually possible from a practical and economical standpoint. Yet, the ethical quandary looms large.

“There has been insufficient national and international discussion and debate, both within the scientific community and between the scientific community and the general public,” says Mathews.

"Even if it is ultimately determined in some jurisdictions that this technology is appropriate for use in human reproduction, it is unclear whether enhancement applications, such as introducing HIV resistance, will be among the approved uses,” she adds.

The researchers attempting this work tend to agree. “We believe that any attempt to generate genetically modified humans through the modification of early embryos needs to be strictly prohibited until we can resolve both ethical and scientific issues,” they write in the paper.

So it’s probably going to be a while until it is possible to have a healthy, genetically edited human. But with CRISPR technology developing at blistering speeds, this is one space to watch.

CRISPR is exciting, but for other reasons than just gene editing
Scientists are using the technology to control genes rather than alter them