Modern biological research continues to generate new technology at a staggering pace, bringing to society new challenges and new opportunities. A recent appearance is the so-called CRISPR/Cas9 technology for altering genes in the body’s cells, including, most troublingly, early embryonic cells.
To understand the challenge brought by this technology it is important to make a distinction between somatic cells and germ-line cells. Somatic cells are the run-of-the-mill cells of our bodies: muscles, nerves, skin and the like. Germ-line cells are the egg and sperm cells that, when joined, give rise to offspring. Making gene changes in somatic cells can have dramatic effects, but they are not transmitted to the next generation and therefore fall comfortably into the category of pure therapeutics and generate minimal controversy. It is changes in germ-line cells that create heritable alterations.
The advent of CRISPR/Cas9 again sees a biomedical technology challenging norms and raising concerns. CRISPR/Cas9 makes it comparatively easy to modify germ-line inheritance by inserting, deleting or altering bits of DNA. It may be possible to make these alterations quite precise, with no undesired changes in the genome. Nevertheless, such changes would be inherited not only by the next generation but by all subsequent generations. Thus the decision to alter a germ-line cell may be valuable to offspring, but as norms change and the altered inheritance is carried into new genetic combinations, uncertain and possibly undesirable consequences may ensue.