The apparent controversy over designer DNA comes down to a misinterpretation of genetic research. I say misinterpretation because I don’t want to assume blatant misrepresentation by people who might honestly be fearful of a future in which one can create a baby like a video game avatar.
Crispr-Cas9 is a relatively new gene editing technique that allows scientists to precisely target and cut a strand of DNA, making it fairly simple to remove a certain gene from a cell of one organism and potentially insert it into the DNA of another cell.
When modified cells replicate, all the cells that came from the original altered cell will have the same DNA alteration as the parent cell, allowing the effect to propagate throughout the organism.
One thing is certain, a human child cannot be customized with current technology. One can’t even eliminate disease, which was one of the most valuable potential positives of gene editing technology. I can’t say what’s possible in the entire realm of scientific innovation present and future, but as of now it hasn’t been done successfully.
It has been seriously attempted once in nonviable human zygotes, and led to unexpected mutations in those that didn’t die off due to the experimentation.
Though disheartening, it’s not too surprising. Crispr-Cas9 was developed due to an insight into how a certain gene pattern in bacteria allowed them to adapt to viruses, and then pass on that adaptation to new generations of bacteria. Though the technology developed from this is incredible in theory, the fact is, bacteria are not somatic cells and bacteria do not generate and propagate in the same way that cells of a developing embryo do.
Adult nematodes have a fixed number of cells, and scientists have been able to trace the cellular development of nematodes from the time they’re an egg through the larval stage, up to adulthood. The cell divisions have been tracked closely enough that researchers know the history of how each cell came to be, similar to how people can trace their family trees.
In nematodes, this process is fairly similar for every organism, scientists can not only trace back the cell lineage of every cell in the nematode, but project the characteristics of an adult nematode with nothing but an undeveloped egg. This can only be done if the egg develops normally without interference. The short distance between a two-celled embryonic nematode and a nematode with about 1,000 cells is 10 cell divisions. Interference during any of these stages leads to a different outcome in the adult nematode, if not death.
Similarly, interference during human development can change the child’s outcome. Also, even though all the genetic material for the future child is contained in the zygote, the environment that the developing embryo is in is what largely determines how those genes are expressed. A human zygote also starts out as two cells, an adult human is composed of trillions.
Crispr-Cas9 operates differently in a more complex organism. Studies on simple organisms such as nematodes and embryos give insight, and allow for speculation on what may be possible in the future. This doesn’t mean that it’s the goal of the research, though.
Though unsuccessful, the study on human zygotes gave valuable insight to the limits of Crispr, and the limits of geneticists’ ability to use it with precision. The fact that this failed on nonviable embryos means that it’s not going to be used on embryos that people currently set aside for their own future children.
Additionally, research on lab-created human embryos that are nonviable is no worse than nonviable embryos being discarded due to their unsuitability for use during in vitro fertilization.
There is definitely large potential with the research, which can allow for advances in the field of genetics without actually altering the genes of humans, present or future.