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Society, Religion and Technology Project Church of Scotland Looking at the ethics of technology for a New Millennium

In Nov.1999 SRT reprinted and updated its book "Engineering Genesis", published by Earthscan, a unique expert study on the ethical and social impact of non-human genetic engineering & cloning. SRT has also made a series of information sheets on ethical issues in genetically modified animals, food, cloning and patenting. This one looks at what genetic engineering is and some of its uses.

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1. Genes, Genetic Information and Genetic Disease
The genetic "code" is the information which determines the nature of the organism stored in a long chain chemical molecule called DNA. A lot of the information is common to all species, but the detailed differences determine whether it is an amoeba, a pine tree, a robin, an octopus, a cow or a human being, and also characterises a particular individual from all others. In humans, apart from identical twins, each person's detailed genetic make-up is unique. We are much more than just our genes, of course, but genes are extremely important. Genes are particular sections of this chemical chain, spaced out along it, which determine the characteristics and functions of the organism. Our understanding of this is being greatly expanded by a systematic mapping process known as the Human Genome Project, carried out internationally with enormous commercial and government funding, and by smaller projects tracing the genetic map of animals, plants and micro-organisms.

This work is identifying individual genes, associated with various functions in the organism, as well as the defects of individual genes which can cause a malfunction and are the roots of many "genetic" diseases. Most functions in the human body seem to be complex, with many genes as well as environmental factors involved, but sometimes a single gene is responsible. Thus in the case of genetic diseases, some genes cause a disease outright like cystic fibrosis, but most give only a susceptibility, and it requires other factors to be present as well for the condition to develop. The ability to detect defective genes means we can test and screen for some diseases, but this also raises important ethical problems. And identifying a gene associated with a disease can give a much greater understanding, but sadly it is not the same as curing it. That may be many decades away, if ever.

2. What is genetic engineering?
Genetic engineering is an umbrella term covering a wide range of ways to change a gene or a small number of genes in a species or between different species. Mostly the term is applied to non-human species. Gene therapy is the term normally used for its fairly rare direct uses in humans. A type of genetic engineering has been done for centuries in animals and plants, through selective breeding. A particular genetic trait is enhanced over many generations by choosing which animals to mate or strains of plant to cross, based on outward appearance. Since the 1980's, however, it has become increasingly possible to manipulate many specific genes at a molecular level in the laboratory. Genetic material is extracted from a living organism, isolated and manipulated, and either replaced in the same organism, or put into a different one. It is like taking a long, thin garment with a constantly varying pattern along its length, snipping out a section of pattern (an individual gene) modifying it, then putting it back, or else putting in a section of a different pattern (gene) taken from another garment, creating a "transgenic" organism. It can make genetic change more specific but its most dramatic effect is to enable for the first time the mixing of genes from widely divergent species.

3. Some Ways Genetic Engineering is Used or is Under Development
But why should we do this manipulation? The many purposes of genetic engineering include :

• to repair a genetic "defect" (as with trials of gene therapy in humans and, potentially, animals).
  
• to enhance an effect already natural to that organism (e.g. to increase plant growth rate).
  
• to increase resistance to disease or external damage (e.g. crops - blight, cold or drought).
  
• to enable it to do something it would not normally do (e.g. genetically modifying animals, plants or micro-organisms to produce human medical proteins).
  

i. Plants and Food - See our information sheet on Genetically Modified Food : Pros and Cons.
This has proved easier technically than animals, as shown by the wide array of uses being developed, but are also controversial, over concerns about environmental risks and who controls the technology.

• Yield improvement to enhance conventional production - but only in some crops, not others.
  
• Disease, pest, and herbicide resistance in crops.
  
• Tolerance of environmental extremes in crops - drought, cold, salinity, flooding, aluminium.
  
• Quality improvement - e.g. flavour, nutritive characteristics.
  
• Food quality - e.g. non-squashy tomato for easier transport and storage without losing flavour.
  
• Genetically modifying plant viruses to produce human medical proteins in the plant leaves
  
• Substitute fuels and bioplastics from genetically engineered oil seed and other crops.
  

ii. Animals - see our information sheet on Genetically Modified Animals
So far it has not been as straightforward to produce transgenic animals as originally thought. Except in salmon, most uses are not for enhanced production characteristics but novel applications. Nuclear transfer cloning may in due course greatly increase the range of animal genetic modifications.

• Widespread use of genetically modified mice as models of human disease such as cancer, for use in testing potential cancer drugs), and to detect the function of human genes.
  
• Adding a human gene to sheep or cattle to produce medically useful proteins in their milk.
  
• Adding a human gene to cattle to improve milk nutritional quality, e.g. for premature infants.
  
• Human haemoglobin from pig's blood (for transfusions).
  
• Genetically modifying pigs with human genes to reduce the risk of tissue rejection if their hearts or other organs were used for transplant into humans (xenotransplantation).
  

iii. Humans
Pre-natal diagnosis of "defective" genes, e.g. cystic fibrosis, Duchene muscular dystrophy.

• Genetic screening of children or adults for dominant inherited disorders like Huntington's Chorea, for recessive conditions like Tay Sachs disease or sickle cell anaemia, or for an increased susceptibility (but not inevitability) of developing forms of breast cancer.
  
• Many human products in routine medical use are made by genetic manipulated micro-organisms, e.g. insulin, growth hormone and various vaccines and proteins.
• "Somatic" Gene Therapy (affecting only the individual concerned), attempting to treat a genetic defect by regular injection or inhalation of "repaired" genes - very much in its early days.
  
• "Germline" Gene Therapy where manipulating the genes of reproductive cells, eggs or early embryo cells could in theory avoid passing the defect on to offspring. Controversial. Forbidden by UK law, reflecting our lack of knowledge of the effects on and rights of future generations.
  
• Human genetic enhancement, i.e. not for medical conditions. Often allied to cloning. So far a very remote prospect, but one which would present very serious ethical and social problems.
  

iv. Cloning? - See our information sheets on Animal Cloning and on Human Cloning
This differs from genetic engineering as it copies the whole genetic make up of an organism, not just changing a part. It raises a profound ethical objection for humans, and questions also for animals.

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Ref.no. GENGINF4 Revised 30/11/99.