Over the past decade genetic engineering has moved from the realms of fantasy to reality thanks to the sequencing of the human genome and developments in molecular biology techniques. A definition of genetic engineering is "the manipulation of DNA using restriction enzymes which can split the DNA molecule and then rejoin it to form a hybrid molecule." It is the introduction of genes into existing cells; this may be used to prevent or cure a wide range of diseases or perhaps to genetically alter a plant so that it gives more food. There are three types of genetic engineering. The first is used for gene therapy and involves the use of retroviruses. Retroviruses are viruses that can transfer their own genetic information and also genetically alter the human gene. This type of therapy can be used in the treatment of brain tumours.

Suppose a brain tumour is forming by rapidly dividing cancer cells. The reason this tumour is forming is due to some defective or mutated gene. The therapy chosen for this case would be to use a herpes virus that has had its virulence removed, rendering it harmless. The virus is still able to insert its genetic material into the target cells. The virus is then taken and injected into mouse cells, where it makes additional copies of itself. These mouse cells, now containing the virus, are then injected into the brain containing the tumour.

Once inside the brain, the virus seeks out the target tumour cells and invades them. The tumour will now start to produce herpes enzymes because the virus has inserted its genetic material into the tumour cells. Once this happens, a physician can treat the patient with a herpes curing drug that will destroy the tumour cells along with the mouse cells that are producing the herpes enzyme. The second method involves blasting genes with a pressurized gun filled with helium.

The helium gun will fire very small gold bullets, which will be coated with the genetically altered genes. This technique was done on mice that had tumours. The gold bullets coated with the altered genes were shot at the skin of the mice that surrounded the tumours. The cells that were successful in receiving the altered genetic code activate immune cells.

By this activation of the immune cells, it is hoped the tumours will decrease. By using the gene bullets the genes are not permanently in the cells of the mice but the effects ware off in a few days to a few weeks. This may be an advantage or a disadvantage. The final method involves liposomes. These are hollow, fat molecules in solution. This method has been experimented with cystic fibrosis, where chloride ion levels need to be kept low.

By inhaling liposomes coated with genetically altered genes, the build up of chloride ion is prevented. There is a significant decreased in chloride ion levels. This method does not pose the harmful side effects that retroviruses do. Despite this new technology possibly curing thousands of diseases, there are many disadvantages to using it.

The basis of gene therapy is finding a gene that is not functioning right and to insert a healthy portion into that gene. To find these genes, scientists must perform genetic tests or genetic screening to see if the gene that causes the defect is present. This genetic testing is highly controversial and is raising many ethical and legal issues. Many believe that this is an invasion of privacy.

If, for example, tests are performed during pregnancy to find genetic faults, these could lead to an increase in the number of abortions. Many young couples may find out that they are carriers of a disease and then have to decide if they want to have a child that could be born with a genetic disease. One major dilemma is finding adequate insurance once a person finds they have a genetic disorder. This may be insurance to cover the treatments, which could be gene therapy, or living their lives knowing that they carry a gene for a disease. A positive test will have placed them in a high-risk group, a group they may have not been in if they hadn't been tested. It is this labelling that makes insurance coverage almost impossible to find.

The insurance that will cover them may be extremely expensive. So, choosing to have the test may be a question of whether they think their current insurance will cover them or not. Another problem is regulation of the uses of gene therapy. For example, society is obsessed with the idea of youth and beauty. If scientists could identify the gene that contributes to youth or beauty, then the technique of gene therapy could be monopolized by the cosmetic industry to enhance beauty or to "turn back the clock." The problem with this is whether baldness, height, or beauty should be enough of a reason to require gene therapy. Then where does it stop? Do we have the right to design who we are, what are children should be? Should people have the power to play God? Many people are worried that new virus or unseen disasters could be provoked by human's medal ling in genetics.

Do we know all the consequences? Although precautions are taken, the risks of harmful modified bacteria (as an example), escaping, still exist. There is also a fear that biological weapons could be developed as a result of genetic engineering. This, for many, this is a central problem in the future capabilities of genetic engineering. A final disadvantage relates to taking genetic information out of other animals and placing them into humans.

For example if an animal produces an enzyme, which is in short supply in some humans, the gene from the animal could be placed into humans. Many moral issues are raised here also. Should we be taking cells from animals and putting them in ourselves? However, for many, the advantages far out-weigh the disadvantages of gene therapy. First of all, advances in the field have introduced treatments to various diseases that were previously thought to be hopeless. Secondly, gene therapy has brought about the production of medicines in mass quantities. The medicines are pure and much cheaper if technology allows it to be produced in large amounts.

Also genetically engineered organisms have many potential applications in agriculture, including novel foods, pesticides, and animal drugs. These include, among others, animals engineered for leaner meat, plants engineered for insect resistance, and bacteria engineered to produce drugs for livestock. Many of the problems that exist with genetic engineering could be eradicated with further funding. While, if precautions are taken the risk factor can be minimised to a miniscule scale. Whatever the view point, there is no denying that genetic engineering has the potential to be a revolutionary new form of curing diseases or even solving industrial problems in agriculture. Perhaps, eventually genetically modified food could even be a cheap solution to world hunger.

What should be remembered throughout is that if used for good, genetic engineering could save millions of lives. For that reason alone, I believe that developments into genetic therapy should continue.