By DRS. DAVID NIESEL AND NORBERT HERZOG
Imagine a world where parents are given a choice of the attributes they would like to see in their babies, such as intelligence, eye and hair color or athletic abilities among many more. While it’s neither possible nor legal yet, recent advances in germ line editing have put us one step closer to this possibility and created a global debate on how it should be applied to human embryos.
Germ line editing is simply the genetic manipulation of early stage embryos, before the embryo implants into the mother’s uterine wall. While germ line editing has been done with cells in a laboratory and in small animals, Dr. Junjiu Huang at Sun Yat-sen University in China reported the first-ever gene editing in human embryos. Huang wanted to remove and replace defective DNA in a gene that leads to a blood disorder called beta-thalassaemia.
These embryos were purposely nonviable because they were fertilized by two sperm, which limits their ability to grow and divide. This report still caused concern among many including ethicists and scientists. Embryo germ line editing in humans is very controversial because any genetic changes would be passed on to future generations. Some have called for a moratorium on all human germ line modification research. Others contend that germ line modification should be acceptable for research purposes because this editing technique could answer many basic scientific questions and could possibly be the answer to ridding the world of genetic diseases. Scientists point to the Asilomar Conference that established the guidelines for recombinant DNA research back in the 1970s as a model to address concerns about germ line editing. The National Institutes of Health, the major funder for biomedical research in the U.S., currently forbids the use of federal funds for germ line editing research.
One major issue with this genetic approach is that it has been shown to introduce mutations in other areas of the genome. This is the source of much of the controversy because no one can predict the consequences of these mutations. Also when individuals with these genetic mutations reproduce, the original defective gene would be propagated. Proponents argue that once the technique matures, the mutations will be eliminated and this concerned reduced. In Huang’s study for example, there were also a large number of mutations elsewhere along the genome that were unexpected. If these were in a viable embryo that would develop into a child, these could lead to harmful changes or could be silent. The fear is that some of these mutations would not be seen until years later or after the child is grown.
On the positive side, once perfected this technique could eliminate devastating genetic diseases before a child is born. Imagine a world without with sickle cell anemia, cystic fibrosis or Parkinson’s. While a recent survey showed that 83 percent of American adults are opposed to using this technique to make a baby more intelligent, only one-half were opposed to using it to reduce serious disease.
Medical Discovery News is a weekly radio and print broadcast highlighting medical and scientific breakthroughs hosted by professor emeritus Norbert Herzog and professor David Niesel, biomedical scientists at the University of Texas Medical Branch at Galveston. Learn more at www.medicaldiscoverynews.com.