Genetics – an introduction
Genes are fundamental to life and help determine the characteristics of bacteria, plants and animals. In people there are approximately 20,000 - 25,000 genes. They are incorporated into the body's cells and are composed of a chemical called deoxyribonucleic acid (DNA). Analysis has shown that the DNA is formed into a double helix which contains vital information about how the cells work.
Genetics research – the hopes
Supporters of genetic research argue that it can bring great benefits. Genetic screening, they say, could reveal vitally important information about a person’s life span and health prospects. Such screening already identifies certain diseases that run in families, enabling couples to decide whether or not to have children.
Furthermore, identification of major genetic defects can help diagnosis and, by replacing the faulty gene, offer the prospect of cure; basic material such as bacteria and yeast can be genetically engineered to produce mass quantities of biological products such as human insulin, growth hormone and hepatitis B vaccine; and crops could be developed that are disease-resistant.
Genetics research – the fears
With all the above categories there is the risk of error leading to potentially serious harm. All previous technologies, not least medical, also came with an inbuilt error factor. But working at the sub-molecular level – as geneticists do – means that the chances of making a mistake are magnified, as are the potential repercussions.
- Genetic screening to establish a person’s lifetime health prospects is an especially complex and imprecise art – and likely to remain that way. The question of faulty diagnosis aside, such information could adversely affect employment prospects and deny a person insurance cover, thereby producing a ‘genetic underclass’. Moreover, an obsession with gene defects could divert attention from the lifestyle and environmental causes of disease that we already know about.
- To identify and replace ‘faulty’ genes accurately, and thereafter have them work as intended rather than promote a potentially major illness, is extremely difficult.
- The commercial mass production of powerful biological products could tend to lead to over-prescribing.
- Release of genetically engineered organisms into the environment may have disastrous long-term consequences. In addition, crops designed to be tolerant of specific pest and weed-killing chemicals will inevitably encourage a greater use of such chemicals.
Some of these fears are at present hypothetical. But there is one group – the animals – for which the genetic nightmare has already begun.
Techniques have been developed to alter animals’ genetic make-up, producing new strains of species to be exploited by the agricultural, pharmaceutical and biomedical industries. One approach is to insert genes from one species into the embryo of another, the resulting creatures known as ‘transgenics’. Another method is to disrupt or knock-out one of the animal’s own genes. Scientists refer to these creatures as ‘knock-outs’.
In 1982 giant mice were produced by incorporating human growth hormone genes into the animals’ fertilised eggs. Gene transfer technology has since been applied to ‘commercially important’ livestock such as chickens, cattle, fish, pigs, rabbits and sheep, with the purpose of ‘enhancing growth performance’.
Government figures show that in Britain during 2018, a total of 3.52 million ‘procedures’ were completed on animals. Of these approximately half were experimental procedures and half were related to the creation and breeding of genetically altered (GA) animals.
Animals suffer not least because scientists cannot predict the results of their genetic tinkering. The large-scale animal suffering flowing from the ‘genetics revolution’ has been largely uncharted, with examples of animals being born with a virtual loss of limbs, facial clefts and massive brain defects. [McNeish, J.D. et al (1988) Science 241:p837-839.]
British cancer researchers acknowledge that experiments with transgenic animals, in which cancer genes are incorporated into living tissues to make them more susceptible to the disease, can have unpredictable consequences: transgenic mice bred to develop eye tumours also suffered cancer throughout their bodies. [Source: Guidelines for the Welfare of Animals in Experimental Neoplasia, UK Co-ordinating Committee on Cancer Research, 1988.]
Even where there are no unexpected complications, genetically engineered animals still suffer and die because in biomedical research they are designed to do so. The ‘oncomouse’, produced by inserting human cancer genes into the embryos of mice, quickly develops fatal breast cancer, while genetically engineered ‘cystic fibrosis mice’ die within 40 days.
Applications and alternatives
Farm animal productivity
Much genetic engineering is aimed at getting farm animals to grow bigger and more rapidly. Yet health studies stress that people should be reducing their intake of animal products: a vegan diet reduces the risk of chronic diseases and increases life expectancy. Similarly, use of the genetically engineered growth hormone BST (bovine somatotropin) to boost milk yields is nonsensical, since not only should people be reducing their consumption of dairy products but in Europe and the USA there is already a glut of milk. Use of the artificial hormone, according to one of the major manufacturers, Monsanto, puts cows “at an increased risk of clinical mastitis [a painful udder infection]”. Other side effects include indigestion, bloat, diarrhoea, leg and foot problems and anaemia. [Source: Information Sheet supplied by Monsanto to US farmers.] Human consumers are also at increased risk of contracting breast and gastro-intestinal cancer, according to Samuel Epstein, Professor of Environmental and Occupational Medicine, University of Illinois. [Source: Farmers Weekly, 1996, 26 January, p8.]
Another application is to develop new ‘animal models’ that more closely mimic human illness. Using transgenic and knockout mice, researchers have created animals with neurological disease, cancer, cystic fibrosis, severe arterial plaque, sickle-cell anaemia, liver damage and many other conditions.
But whatever miracles the new technology hopes to perform it cannot transform mice into miniature people, and the results cannot be relied upon. In the case of ‘cystic fibrosis mice’, the animals do become ill but there are differences from the disease in people: most importantly, the animals’ lungs do not become infected or blocked with mucous as they do in human patients. It is lung infections that kill 95 per cent of people with cystic fibrosis. [Source: Editorial, Lancet, 1992, September 19, pp702-703.]
Retinoblastomas are tumours of the developing retina and are reported to arise when a cancer-suppressing gene is disabled in some way. However, when a similar gene is disrupted in mice, the animals do not develop retinal tumours. Robin Holliday of the CSIRO Laboratory for Molecular Biology in Australia explains that such differences should not surprise since “tumour-suppressor genes and oncogenes [cancer genes] behave very differently in mouse and man”. [Source: Nature, 1992, November 26, p305.]
Transgenic and knockout animals are also being used to test gene therapies. However, the successful incorporation of genes into cells can be studied in the test tube: one therapeutic approach is to remove cells from the human patient, incorporate healthy genes into these cells in a test tube and, finally, return them to the patient, in the hope that the introduced genes will produce enough healthy cells to remedy the illness. Ultimately, of course, it is clinical, patient-oriented studies that give the most valid results.
Biological ‘factories’ (transplants/production of biological products)
A further application of genetic engineering is to produce animal organs for transplant purposes.
The usual justification for using animal organs is a lack of human donors. One possible solution is an ‘opt-out’ scheme (where organs are presumed to be available after death unless otherwise indicated). In addition, health policy could be directed towards preventing disease, thereby obviating the need for so many transplants.
The idea of animal-to-human transplants was endorsed by the influential Nuffield Council on Bioethics, so long as certain safeguards and ethical procedures were followed. But, despite the existence of the transgenic pig, the Council saw major problems and dangers. “Even if hyperacute rejection [in which the recipient’s immune system rapidly destroys the incoming organ] can be controlled, there will be other immunological barriers to acceptance of the xenograft by the recipient. There may also be biochemical and physiological incompatibilities between pig organs and human beings.” [Source: Animal-to-Human Transplants – the ethics of xenotransplantation. Nuffield Council on Bioethics, March 1996, p36.]
Nuffield pointed to another major problem: “It is not possible to predict or quantify the risk that xenotransplantation will result in the emergence of new human diseases. But in the worst case, the consequences could be far-reaching and difficult to control.” [Source: Nuffield Council report, p116.] Nuffield was referring to the fear that animal organs will contain unknown and therefore unscreened-for viruses and other disease organisms that prove deadly to people.
There must be similar risks of contamination from animals genetically engineered to produce pharmaceutical products, such as blood clotting factors, in their milk. Known as ‘commercial bioreactors’, these animals represent another major business application of genetic engineering. Some carefully-screened biological products can be obtained from human donors, while non-sentient organisms, such as genetically engineered bacteria and cells, could also be used.
Much of the storm over genetically engineered animals has focused on the right to patent living creatures. Patenting animals reduces them to the level of inanimate objects – mere ‘inventions’, to be exploited as deemed necessary. Patenting animals must also encourage more experimentation, since companies have a major incentive to breed and market these creatures before the patent expires.
The genetics revolution has provided even greater incentives for exploiting animals. But there are also risks for human beings and the environment. For all our sakes, genetics research must be subject to increased and impartial scrutiny.