According to an article on the MIT Technology Review a team of Chinese scientists have performed a genetic modification using the CRISPR/Cas9 technique to delete the CCR5 gene. This deletion should remove a CCR5 receptor on cells membranes removing the point used by the HIV virus to infect the cell. This would make the person immune to HIV. The genetic engineering was carried out on twins. The two girls were indeed born without the CCR5 gene and hence without the receptors. Notice that there are humans that are born without that gene, actually it was by observing those persons that scientists have discovered their resistance to the HIV virus. Hence the Chinese scientists have just “forced” something that may happen naturally.
Now it comes the interesting part. Researchers have found that the deletion of the CCR5 in mice creates “smarter” mice and it was also found, at the University of California Los Angeles, that persons without the CCR5 gene have better chance of recovering after an ictus and are usually performing better at school.
It is not a sure thing that the twins will enjoy a better cognition, after this deletion of CCR5 through genetic engineering but according to the neurobiologist whose team at UCLA discovered the relation between the absence of the CCR5 and improved cognition it is a distinct possibility.
This is pointing out two aspects: the issues of connecting the genotype with the phenotype and the serendipity associated to genetic engineering.
A single gene can be involved in many aspects of the phenotype of a person (how that person looks like, how it behaves…) and we have no idea, in general of what would be the result of removing it (or adding/changing it). This is one of the reason for the concerns on genetic engineering. We now have the technology to cut and paste pieces of the DNA, hence to change its genes, but we do not know what the outcome might be.
The serendipity is clearly associated to our ignorance on the connection existing between the genotype and the phenotype. By modifying the genes to obtain a specific outcome, like in the case of the twins to make them HIV immune, we may discover something unexpected, like the improvement of cognitive capabilities (yet to be confirmed in the twins, although likely). This is the same serendipity happening in Nature, leading to the evolution of species.
Clearly I am no expert in genetic engineering, nor am I versed in ethical aspects. I am just an observer and as such I see that we are moving towards the possibility of enhancing the human species also at cognitive level and I won’t be surprised to see the shift from possibility to actual implementation.