Let's not spawn false hope in birth of twins

| Dr Melody Leung 30 Jan 2019

Melody Leung, Lecturer, Division of Life Science, HKUST

On November 26, scientist He Jiankui announced the birth of two genetically edited twins, sending shock waves around the world.

Last week, mainland authorities condemned He's "illegal" action as an act committed in pursuit of fame and fortune and warned he could face severe punishment.

The scientist said his experiment was meant to produce HIV-resistant babies, which doesn't sound half as bad, so why the public outrage?

We might start by first understanding what the experiment is about.

When the twins were in the embryonic stage, the scientists used Crispr-Cas9 technology to remove a portion of the CCR5 gene before implanting the two embryos in the mother's womb, and a pair of gene-edited twins were born.

The gene encodes a protein that HIV strains use to infect T-cells of the human immune system. The modified, shorter versions of the gene should disable the CCR5 protein, thus preventing HIV from invading T-cells.

Therefore, He claimed the gene-edited twins could resist HIV infection.

The human genome is the blueprint of the body and is not static.

Most changes in the genome are natural - like during cell replication and sexual reproduction.

Artificial alterations began over 1,000 years ago when humans started cultivating livestock.

Herds with distinct characteristics were mated according to our needs and preferences. After generations, the better features were enhanced and the undesirable ones receded.

If we have a history of enjoying the benefits of modifying animal genomes, why all the fuss over gene-edited human babies?

Because these are our children. We must attach a greater responsibility and apply much stricter ethics.

Crispr-Cas9 technology is prone to create changes in genes that deviate from the target (aka off-target), meaning gene-edited babies may face unpredictable complications or increased health risks.

Having said that, it isn't genetic engineering itself, but the technology which is still immature at this stage that worries us most. If gene-editing is well developed and we have absolute certainty about which gene should be modified and how it should be done, we would probably be practicing it on a mass scale, but it's not.

In any case, He's story has a major catch.

We know some Scandinavians are born with a congenital deletion mutation that renders their CCR5 protein dysfunctional, however, their immunity to HIV is not absolute.

There have been cases involving people being infected by the virus despite having a pair of mutated CCR5 gene.

That means He hasn't really achieved a breakthrough: he was merely using an underdeveloped technology to install, in the human body, uncertain changes, which are a lame joke if not just stark crazy.

HKUST experts have their fingers on the pulse of a new age of science, technology and innovation.

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