He Jiankui's Gene Edited Babies May Have a Lower Life Expectancy Because of Chinese Scientist's Experiment

Update: The study this article is based on has now been retracted by the authors. Read more here

In November 2018, Chinese scientist He Jiankui announced the birth of the world's first gene edited babies—twin girls called Lulu and Nana. The news was met with widespread condemnation, with the scientific community saying the experiment was hugely unethical and potentially dangerous. There was little to no understanding of the long term consequences of artificially altering a human, including the adverse health effects that could emerge over time.

For his gene editing experiment, He had deleted the CCR5 gene of the sisters so they would be more resistant to HIV. This gene is needed for HIV to enter human blood cells, so removing it should mean it would be more difficult for the sisters to get the virus.

Previous research has shown that people with a mutation to the CCR5 gene—specifically that they carry two copies of it, known as the Δ32 mutation—appear to be more resistant to HIV. While He has not published any research relating to his gene editing experiments, it is thought he was trying to mimic the effect of this mutation.

In a study published in Nature Medicine, researchers Xinzhu Wei and Rasmus Nielsen, from the University of California, Berkeley, and the University of Copenhagen, Denmark, looked at the death register information from over 409,000 individuals in the U.K. Biobank. This is a program that investigates the roles of genetic predisposition and environmental exposure to disease development. The biobank data includes genetic details on whether the individuals had the CCR5 mutation or not.

Their findings showed that people who carried the Δ32 mutation (that protects against HIV) were 20 percent less likely to reach the age of 76 than people without the mutation, or a single copy of the gene.

In previous studies, researchers have found the Δ32 mutation is associated with a number of other pathogens—it is thought to provide some protection from smallpox and flavivirus. It is also thought to help recovery following a stroke, while research on mice indicates it can help improve memory. However, the mutation also has a downside. It is thought to reduce protection against other infectious diseases, while people with the Δ32 mutation have an increased mortality rate from influenza.

The researchers say their findings suggest that in the absence of HIV infection, the Δ32 mutation appears to have a negative effect on the health of the individual. However, they note their results may be affected by fewer individuals with HIV getting involved in the U.K. Biobank program.

Concluding, they say it is not surprising that the mutation is associated with reduced fitness and mortality. "It underscores the idea that introduction of new or derived mutations in humans using CRISPR technology, or other methods for genetic engineering, comes with considerable risk even if the mutations provide a perceived advantage," they write. "In this case, the cost of resistance to HIV may be increased susceptibility to other, and perhaps more common, diseases."

What the latest findings mean for the gene edited babies is unknown.

Wei told Newsweek: The effect of the mutation depends on the genetic background and the environments, we don't have information to speculate about its effect in the East Asians.

"In addition, the mutations in He's experiment—based on online information—are different from Δ32, and we don't have information about the effect of that mutation in any population."

He said the findings show "there are still a lot of things unknown about the functions of genes, including what the phenotypes a mutation affects, and their functions in different genetic backgrounds and in different environments. For any editing, the consequences of all sorts need to be considered."

This article has been updated to include quotes from Xinzhu Wei.