Los Angeles: The world’s first babies whose genes were reportedly altered to help them fend off HIV infection are more likely to die younger, a study claims. According to an analysis by scientists from University of California (UC) Berkeley in the US, the controversial genetic mutation that a Chinese scientist attempted to create in twin babies born last year is associated with a 21% increase in mortality in later life.
The researchers scanned over 400,000 genomes and associated health records contained in a British database, UK Biobank, and found that people who had two mutated copies of the gene had a significantly higher death rate between ages 41 and 78 than those with one or no copies.
Previous studies have associated two mutated copies of the gene, CCR5, with a fourfold rise in the death rate after influenza infection, and the higher overall mortality rate may reflect this greater susceptibility to death from the flu.
However, the researchers said there could be any number of explanations, since the protein that CCR5 codes for, and which no longer works in those having the mutation in both copies of the gene, is involved in many body functions.
“Beyond the many ethical issues involved with the CRISPR babies, the fact is, right now, with current knowledge, it is still very dangerous to try to introduce mutations without knowing the full effect of what those mutations do,” said Rasmus Nielsen, a professor at UC Berkeley. “In this case, it is probably not a mutation most people would want to have. You are actually, on average, worse off having it,” said Nielsen.
“Because one gene could affect multiple traits, and because, depending on the environment, the effects of a mutation could be quite different, I think there can be many uncertainties and unknown effects in any germline editing,” said postdoctoral fellow Xinzhu Wei, first author of the research published in the journal Nature Medicine.
The gene CCR5 codes for a protein that, among other things, sits on the surface of immune cells and helps some strains of HIV, including the most common ones, to enter and infect them. Jiankui He, the Chinese scientist who last November announced he had experimented with CCR5 on at least two babies, said he wanted to introduce a mutation in the gene that would prevent this. Naturally-occurring mutations that disable the protein are rare in Asians, but a mutation found in about 11% of Northern Europeans protects them against HIV infection.
