So now that we know how scientists perform Genetic Engineering it is time to look at what we use it for.

THE HUMAN GENOME

Originally scheduled to be completed in the year 2005, the Human Genome project undertaken by the The International Human Genome Sequencing Consortium, was completed in April of this year.

The finished sequence covers about 99% of the human genome and has claimed an accuracy of 99%. For an idea about how big of a project this was, you can click here to see an example of the actual genetic code from from the 7th human chromosome (note: this is not the full chromosome, just 1/12 of it). For an actual map of the human genome you can check out the NCBI's web page here. Its rather technical, but they do have some nice graphical representations for the genome.

The outcome of this is that scientists can now study with greater accuracy genetic diseases (such cystic fibrosis and muscular dystrophy), and can see how genes affect things like obesity, dyslexia, and cholesterol (Living World, 221). The mapping of the human genome will also play a great role in Genetic Therapy.

Genetic Therapy

Genetic therapy is based on the principle that if there is a malfunctioning gene, it stands to reason that that gene can be replaced with a gene that has been modified to work properly, thus stopping or curing various diseases.

To perform gene therapy, the correct gene must be created using either the Recombination or PCR techniques. The gene is then placed into a vector and administered to the patient. The vector will then insert the new healthy gene into the cells replacing the old gene with the new gene.

There are two forms of gene therapy, in vivo and ex vivo. In vivo means that the vectors are administered directly into the patient's body at the site problem. An example of this would be that to treat Cystic Fibrosis, patients can breath in a vector in an attempt to modify the cells in their lungs (Cornell).

Ex vivo gene therapy involves removing the afflicted cells from the patents body, inserting the new gene into them, and then reinserting the cells back into the patients body. An example of Ex vivo treatment would be the removal of stem cells from a patient's bloodstream, their modification, and eventual return (Cornell)

A few genetic diseases that could theoretically be cured with gene therapy:
Cancer (uncontrolled cell growth)
Asthma (controlled by several genes)
Diabetes (all types)
Spinal Muscular Strophy
Alzheimer's Disease
(NCBI)

for all of these diseases, scientists have narrowed down the genes that control this diseases and are currently researching how to correct them.

However, the technology is still too young to be fool proof. There are several problems:

1. Many diseases are polygenetic, and thus it is more difficult to locate and to understand the relationship between the different genes controlling the disease.

2. There are millions of cells in the human body and vectors will in most cases only modify 1 cell in 1000 (Cornell).

3. Also, due to the large number of cells and the complexity of the human body, it is not certain that the vector will find the defective cells at all or that the new gene will even be expressed.

Genetic Screening and Diagnosis

Have you ever seen the movie Gattaca? If you have then you know what Genetic Screening is. But for those of you who haven't seen this movie, I'll explain. (you really should check out that movie, it's good :)

Because genetic diseases are hereditary and are contained within our DNA, they are therefore present at the time of conception. A disease could be a recessive trait and not thus not affect an individual. However if one individual mates with another individual who also carries the recessive trait then they have a 1 out of 4 chance of having a child who will have the disease (two recessives make a whole).

However, with recent advents of technology and medical breakthroughs, many genetic diseases can be treated if found early enough. So if a DNA sample is obtained from an infant, that infant could be screened for known genetic diseases using the Electrophoresis technique and comparing the infant DNA against known stands containing diseases.

Study of Evolution

More and more, genetics has been playing a part in the study of Evolution. If two organisms are believed to be related to each other through evolution, then they will share either a few or many similarities at the genetic level. For instance, using PCR Amplification, scientists can examine the DNA of fossilized skeletons from 50,000 years ago which could ultimately allow us to trace our origins back to our earliest ancestors (Cornell)

"Magic Bullets"

For a long time, people suffering with diabetes had to rely on insulin that was taken from donor's blood - a difficult and expensive task. However, in 1982 the FDA approved the use of a new type of insulin that could be made cheaply and in large amounts. That insulin was created genetically (Living world 222).

Today, a large amount of medical research goes toward developing these "magic bullets" - proteins that are present in some humans and not in others. Other examples of these proteins are Factor 8 - which is given to hemophiliacs to promote blood clotting, and anticoagulants which are given to heart attack patients to dissolve blood clots. Through genetic manipulation of bacteria, scientists are able to produce these proteins on a massive scale. Thus both increasing availability and reducing costs.