Human genetic engineering

Human genetic engineering refers to the controlled modification of the human genome. DNA provides the genetic blueprint for all living organisms and can influence individuals' actions and abilities. With the advent of DNA research and the ability to change gene expressions, it is now possible that scientists may be able to change human capacities, whether they be physical, cognitive, or emotional. Human genetic engineering is still in its infancy, however, with current research generally restricted to animals or gene therapy.

Healthy humans do not need gene therapy to survive, though it may prove helpful to treat certain diseases. Special gene modification research has been carried out on groups such as the 'bubble children' - those who's immune system do not protect them from the bacteria and irritants all around them. The first clinical trial of human gene therapy began in 1990, but (as of 2006) gene therapy is still experimental. Other forms of human genetic engineering are still theoretical, or restricted to fiction stories. Recombinant DNA research is usually performed to study gene expression and various human diseases. Some drastic demonstrations of gene modification have been made with mice and other animals, however: testing on humans is generally considered off-limits. In some instances changes are usually brought about by removing genetic material from one organism, and transferring them into another species. This method is known as recombinant genetics.

There are two main types of genetic engineering. Somatic modifications involve adding genes to cells other than egg or sperm cells. For example, if a person had a disease caused by a defective gene, a healthy gene could be added to the affected cells to treat the disorder. The distinguishing characteristic of somatic engineering is that it is non-inheritable, e.g. the new gene would not be passed to the recipient’s offspring.

Germline engineering would change genes in eggs, sperm, or very early embryos. This type of engineering is inheritable, meaning that the modified genes would appear not only in any children that resulted from the procedure, but in all succeeding generations. This application is by far the more consequential as it could open the door to the perpetual and irreversible alteration of the human species.

There are two techniques researchers are currently experimenting:
 * Viruses are good at injecting their DNA payload into human cells and reproducing it. By adding the desired DNA to the DNA of non-pathogenic virus (a pathogen is something that harms you. A non pathogenic virus is still a virus by definition, but will not cause you to get sick), a small amount of virus will reproduce the desired DNA and spread it all over the body.
 * Manufacture large quantities of DNA, and somehow package it to induce the target cells to accept it, either as an addition to one of the original 46 chromosomes, or as an independent 47th human artificial chromosome.

Changes at conception
Genetic engineering is most easily accomplished by making changes just after the egg and sperm have melded but before first division. In this way, the gene will be expressed throughout and will affect the recipients children, grandchildren, and all subsequent generations. This type of germline engineering is highly controversial and deemed inappropriate by most scientists.

Changes after birth
As of now, this is likely to take the form of gene therapy. This is will not be hereditary unless the sex cells are engineered.

Curing medical conditions
When treating problems that arise from genetic disorder, one solution is gene therapy. A genetic disorder is a situation where some genes are missing or faulty. When this happens, genes may be expressed in unfavorable ways or not at all, and this generally leads to further complications.

The idea of gene therapy is that a non-pathogenic virus or other delivery system can be used to insert a piece of DNA--a good copy of the gene--into cells of the living individual. The modified cells would divide as normal and each division would produce cells that express the desired trait. The result would be that he/she would then have the ability to express the trait that was previously absent at least partially. This form of genetic engineering could help alleviate many problems, such as diabetes, cystic fibrosis, or other genetic diseases.

Human Enhancement
The potential of genetic engineering to cure medical conditions opens the question of exactly what such a condition is. Some advocates see aging and death as medical conditions and engineering problems to be solved. They see human genetic engineering as a key tool in this (see life extension). The difference between cure and enhancement from their perspective is merely one of degree. Theoretically genetic engineering could be used to drastically change people's genomes which could enable people to regrow limbs, the spine, the brain. It could also be used to make people stronger, faster, smarter, or to increase the capacity of the lungs, among other things. If a gene exists in nature, it could be brought over to a human cell.

Others feel that there is an important distinction between using genetic technologies to treat those who are suffering and to make those who are already healthy superior to others. There is widespread agreement that germline engineering should not currently be allowed for either therapeutic and enhancement applications, as evidenced by a recent report by the American Association for the Advancement of Science. Though theory and speculation suggest that genetic engineering could be used to make people stronger, faster, smarter, or to increase lung capacity, the AAAS report finds that there is little evidence that this currently can be done safely or without unethical human experiments.

Ethical considerations

 * We could choose to have changes made to us, but we might also be making the choice for our children if the changes are carried through to the germline. Do we have that right, and how far should we take our ability?


 * Conversely, is it responsible and ethically acceptable to leave the potentials of our children to the chance effects of the "genetic lottery", if we obtain the technological capacity to make positive changes?


 * If genetic engineering became the way of the future, would people whose parents could not afford to genetically 'modify' them while still in an embryo, have a chance of achieving with high standards compared to the people who were 'modified' to be perfect?


 * Is it ethical to experiment on embryos that have yet to be born?


 * How would genetic engineering be used to revolutionize warfare?


 * Who decides which changes will be made?

Social considerations
While some individuals may benefit from non-therapeutic genetic engineering, there may be adverse social implications. Few resources – particularly those related to medicine and health care – are available to everyone, and allowing the most privileged to engineer themselves or their children to have special capabilities could lead to what some call a genetic aristocracy. Numerous enhancements via genetic engineering have been proposed, including increased memory, intelligence, and less need for sleep, in addition to some peoples’ desires to alter their physical appearance. The advantages created by genetic engineering, either real or perceived, could lead to new forms of inequality between those with genetic enhancements and those without while also exacerbating current inequalities between rich and poor, men and women, and whites and communities of color. Other considerations include:


 * Would society treat genetic engineered people differently?


 * Would they be left behind, would they be considered second class humans?


 * What if this created a different species of human, would they still be able to interbreed, would they want to?


 * What place would genetically engineered humans and regular humans have in society?


 * Could unequal access to genetic engineering lock in or exaggerate current class divisions?

Metaphysical considerations

 * The metaphysical (or "spiritual") implications of genetically engineered humans are vast in scope; e.g., were individual personality shown to be exclusively the result of genetic information acted upon by the environment, the concepts of the human soul and free will could be proven specious.


 * However, could this be shown by the success of actual attempts at genetic engineering any more (or less) than it is shown by what is already known about the roles of genes and the environment in shaping the phenotypical characteristics (including behavior) of living things?

Examples

 * Undercover genes slip into the brain article by Anil Ananthaswamy: William Pardridge and his team have developed a technique to put genes into the brain. The team inserted the gene for the luminescent protein luciferase into the brains of rhesus monkeys.


 * Gene therapy may switch off Huntington's article by Bob Holmes: While the technique has not yet been tried in people, Beverly Davidson and Henry Paulson report some success in human cells.