Before the end of 2018, He Jiankui, a Chinese biophysicist, has announced that he had successfully conceived two children through artificial insemination, but with the use of CRISPR-Cas9 manipulation before implanting the embryos. This was the first time that the human germline has been genetically manipulated, making it a hot topic for experts and ethically inclined professionals worldwide. This resulted in the Chinese government issuing rules against the same attempt in the future.
He Jiankui argued that the modification he had done was beneficial as he aimed for the babies' immunity against HIV. The father of the children is a carrier of HIV and He Jiankui claims that the children are now immune to the virus because he used CRISPR-Cas9 to remove the CCR5 gene-the gene used by HIV to attack the body's immune system-from the genome before implanting the embryo in order to prevent the virus from attacking the children's immune systems. His analogy comes from the theory that about a hundred thousand people affected with a mutation called Delta 32, naturally do not carry the CCR5 gene and are therefore immune to the HIV virus.
However, a study led by Xinzhu Wei and Rasmus Nielsen from Berkeley suggests the opposite. The researchers have looked through statistical data from the UK Biobank, which is the largest human gene database in the world, to find about the health risks of the experiment done by He. They wanted to find out if other health risks are associated without the CCR5 gene or with the mutation Delta 32.
To study the case, the researchers considered people who had Delta 32 twice, those who had Delta 32 mutation once and the CCR5 gene once, and those who had the CCR5 gene twice. The children from He's experiment falls under the first classification, which means that they have two Delta 32 mutations. Now, this poses a problem since the researchers have also found that people who have Delta 32 twice now lack the CCR5 gene, and have a 21 percent lower chance of reaching the age of 76, compared to those who have no or only one Delta 32 mutation. This is from statistical data alone. Another study done in 2015 and led by A. Falcon says that people without the CCR5 gene die due to influenza four times more often compared to those carrying the CCR5 gene.
Nielsen and Wei further back their study up with a conclusion that CRISPR is not to be messed with as this is too dangerous right now to be used for modification of the germline, whether it is used for humans or animals.