Disease, by its very nature, has a genetic component. A disease is either inherited or the result of the body’s response to environmental elements such as a virus. At present human genetic engineering is primarily carried out through a process known as Preimplantation Genetic Diagnosis or Selection either PGD or PGS. No real engineering takes place, what happens is single cells are removed from embryos using the same process as used in In Vitro Fertilisation (IVF). These cells are then examined to identify which are carrying the genetic disorder, which are not. The embryos that have the genetic disorder are discarded, those that don’t are returned to the uterus in the hope that a baby will be born, without the genetic disorder. Only previously identified genetic disorders can be tested for, there is no ‘catch all’ testing. What this means is that if the parents fear their unborn child might inherit a disease or disorder they can choose to have their embryos tested for that specific disease or disorder.
Some examples of disorders that can be tested for are:
• Downs Syndrome
• Tay-Sach Disease
• Sickle Cell Anaemia
• Cystic Fibrosis
• Huntington’s disease
There are of course many others than can be tested for and medical and scientific institutes are constantly searching for and developing new tests.
This procedure is fairly uncontroversial, it does however have it’s critics who argue that human life starts at conception and therefore the embryo is sacrosanct and should not be tampered with or that we simply should not be messing around with our genetic make up and the results are unstable and unpredictable.
Another use for this technique is gender selection, which is where the issue becomes slightly more controversial. Some disorders or diseases are gender specific, so instead of testing for the disease or disorder the gender of the embryo is tested for and whichever gender is ‘undesirable’ is discarded. This brings up huge issues about the ethics of gender selection and the consequences for the gender balance of humankind.
A more recent development is the testing of the embryos for tissue matching. The embryos are tested for a tissue match for a sibling that has already developed or is in danger of developing, a genetic disease or disorder. The purpose is to produce a baby who can be a tissue donor. This is known as Sibling Savers. Again this technique has caused much controversy as the purpose of the testing was seen as being not for the purpose of disease elimination directly. This technique is one step forward in the search for ways to treat and cure, rather than eliminate, genetic disease and disorder and for finding ways to use these techniques in the use of genes as curers i.e the introduction of a modified gene that could perhaps suppress a tumourous growth. This is known as Gene Therapy.
The next step in disease elimination is to attempt to refine a process know as Human Germline Engineering. Whereas PGD affects only the immediate offspring germline engineering seeks to affect the genes that are carried in the ova and sperm and thus eliminate the disease or disorder from all future generations making it no longer inheritable. The possibilities for germline engineering and gene therapy go beyond the elimination of disease and move us into the other spheres of influence we identified earlier; longevity, capacity, adaptability and fashion.