Genetic engineering is starting be increasingly used in human contexts, and gene diagnosis and editing practices have allowed for researchers and doctors to increasingly control and modify human traits.
One practice that is now being used is preimplantation genetic diagnosis (PGD). This diagnosis practise allows for people to choose the sex and eye colour of their children before they are born, and Popular Mechanics reports that it is currently being used in the United States and China.
In PGD, eggs are taken from a mother, and then fertilized in vitro. After fertilization, the new embryos that are created are analyzed for their genetics, which will allow them to tell certain traits about each embryo. These traits include risk of genetic diseases, but they also include the sex and eye colour of the child that would result from each embryo.
Once all of this information is made available, the parents select one of the embryos to “keep,” and it is inserted back into the mother’s womb, so that the resulting child has the eye colour, sex and disease risk (or lack of risk) that the parents want it to have.
In addition to gene diagnosis, gene editing has also been developed that allows for doctors to actually manipulate the genes themselves. One of the most well-known tools is Clustered Regularly-Interspaced Short Palindromic Repeats (CRISPR).
CRISPR can edit a genome substantially; the Popular Mechanics report mentions researchers in Brazil who have modified a species of mosquito so that it will die before maturity in hopes that this new genome will eradicate the entire species. This substantial modification means that, if applied to humans, CRISPR can edit the human genome in ways that can possibly eradicate diseases, and even possibly slow down aging.
The use of CRISPR on human embryos is still not allowed in the United States, but it has recently been approved in the United Kingdom.