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Gene Therapy

Biology - Sac 3

Jo Collins

on 14 September 2012

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Transcript of Gene Therapy

photo credit Nasa / Goddard Space Flight Center / Reto Stöckli By Joanna Collins GENE THERAPY What is gene therapy? What is Cystic fibrosis? Methods for Gene therapy How might this become an example of human intervention in evolution? Interrelationships between biological, cultural and technological evolution? What is Gene Therapy? Back ground information: Gene therapy is a relatively new technological advance where the idea of a 'gene surgery' was established in the early 1970's by a group of scientists. The science of genetics advanced in the 1980's and established a basis of gene therapy where it was accepted as a viable approach the treat specific genes.
A major reasoning into the growth of gene therapy is for the reason that scientists now have the increasing ability to identify specific genetic malfunctions and also that gene therapy holds the hope of curing diseases.
A group of scientists, in 1983, from Baylor College of Medicine in Houston, Texas, suggested that one day gene therapy could be a feasible method for treating Lesch-Nyhan disease which is a rare neurological disorder. This group ran experiments where an enzyme producing gene was injected into a group of cells fro replication, which would correct the disease.
They theorized that the cells could be injected into people with Lesch-Nyhan disease, resulting in correcting the genetic defect that causes the disease. The Gene involved in Cystic fibrosis... First Case of Gene Therapy: The first know case of a person treated for gene therapy was a small four year old girl from the united states who had Adenosine Deminase, ADA, which causes her immune system to become weak. She was successfully treated on 14th September, 1990, at the National Institutes of Health's Clinical Center, Bethesda, Maryland where Dr. W. French Anderson and his colleagues at the health center, carried out the proceedings. Gene therapy is the introduction into a tissue or organ of a specific DNA to replace or compensate for a defective disease-causing allele. Gene therapy is a medical procedure that modifies genetic material of living cells of an individual so that, that genetic defect is corrected. Cystic Fibrosis (CF) is an inherited autosomal recessive condition in which an affected person produces abnormal mucus secreations. Currently in the Australia Cystic fibrosis occurs in about 1 in every 2000 births where symptoms include production of very salty sweat, blockage of airways with consequent lung infection and heart complications and malabsorption from the digestive tract. Some side effects of gene therapy in CF can occur which includes immune reactions if viruses are used to carry genes. Human intervention occurs through many procedures, such as cloning, artificial selection, through reproductive technologies,genetic screening e.t.c where through these processes, the normal process of natural selection is altered.
Humans intervene so it can benefit themselves and there are many reasons for this, such as;
- For a profit,
- Medical advantages,
- Food production,
- Aesthetics (Cloning), e.t.c...

In this presentation, SAC 4, it will be exploring human intervention in evolution and the different aspects of Gene therapy and Cystic Fibrosis in humans. There are two main techniques that are used for gene therapy –
In vivo gene therapy; this is where gene therapy is given directly to a patient.
Ex vivo gene therapy; this is where gene therapy is completed outside the patient, in which patients cells are manipulated outside the body and then returned into the individual.
Approaches for correcting defective genes:
Swapping an abnormal gene for a normal one.
Repairing an abnormal gene.
Altering the degree to which a gene is turned on or off Gene Therapy and Cystic fibrosis: In treating Cystic fibrosis the method of gene therapy used is to target the cause of the disease rather than just treating the symptoms. Gene therapy is used to give patients copies of the correct gene so they can make the correct protein by synthesis the corrective gene is transported via either a vector. Vectors are agents such as plasmids or a virus that carries passenger DNA into a cell, the most common viruses that are used for gene therapy are Adenoviruses (DNA viruses) and Retroviruses (Can only be used in cells that are reproducing). Generally, the normal gene will randomly insert itself into the cell DNA, this may alter the phenotype due to changes in the position or chromosomal environment of the gene where this is called the position effect. This can be either harmful or helpful in which it depends where the gene inserts due to random insertion. However researchers have found that that the gene can be successful and safely transferred into CF airways via the lungs. They are now researching and refining the delivery methods to carry genes to damaged cells in other organs affected by CF according to the Cystic Fibrosis Foundation. Methods using Retroviruses and Adenoviruses.... Gene therapy using an adenovirus vector;
A cloned DNA gene is inserted into the adenovirus DNA. The vector binds to a cell membrane and is packaged in a vesicle. The vesicle then breaks down; releasing the vector and the vector injects the new gene into the nucleus. If the adenovirus successfully transfers the DNA into the nucleus (staying separate from the host DNA), a functional protein will result.
Gene therapy using a retrovirus vector;
Cloned RNA version of a gene is inserted into a retrovirus that has some of its RNA removed to ensure no disease is caused and unable to overtake the host cell for its own replication. After infecting the cell, the retrovirus transforms its RNA into DNA that can be incorporated into the host cells chromosomes. The specific gene involved in cystic fibrosis is the Cystic Fibrosis Trans-Membrane Conductance Regulator, which is often denoted as CFTR, where it is located on the long arm of human chromosome number-7. This regulates salt and water movement in and out of cells where the alteration of this protein is what causes the thick, sticky mucus typical shown in Cystic Fibrosis. About 70% of mutations observed in CF patients result from deletion of three base pairs in CFTR's nucleotide sequence. The normal form of the protein consists of a chain with 1480 amino acids, however people with Cystic Fibrosis produce an altered form of this protein. Advantages of Gene Therapy When gene therapy is successful, it can provide a cure rather than easing the symptoms.
It gives someone that is born with a genetic disease or who develops cancer the chance at a normal life.
Cancer gene therapies may provide alternatives when a disease does not respond to other older treatments.
It has the potential to remove cells without damaging any normal healthy tissue.
Gene therapy can be focused to a specific cell type to avoid potentially toxic systemic effects. Disadvantages of Gene Therapy There is still currently a lack of knowledge and understanding of the treatment as it is still developing.
The desired effects can sometimes be short lived.
There is no guarantee that the vector carrying the healthy gene will end up in the specific place intended.
There is a risk of causing even more damage to the genetic makeup which can result in severe consequences.
It can be potentially misused to select specific gene s to create the ‘perfect’ child. AIM of Gene Therapy This technique aims to treat inherited disorders by directly targeting the genotype. It aims to add copies of the normal allele of a gene into the cell of a target tissue, switching them to produce the functional protein that is missing in with a particular disorder, such as Cystic fibrosis. Gene therapy is an example of genetic intervention; genetic intervention refers to the transfer of genetic material intended to modify human traits. Gene Therapy is an example of human intervention in evolution as it has a potential for treating inherited disorders and diseases, and making them extinct, as natural selection has no human intervention on various phenotypes.
Gene therapy has the potential to turn into a genetic enhancement of our genes, creating new bodies and able to change specific genes of our children to create 'designer children'. Bibliography http://www.infobarrel.com/Gene_Therapy#X9ki0LmUVWvXhO1Y.99
Nature of Biology, third edition, book 2, Judith Kinner, Marjory Martin.
http://www.news-medical.net/health/Gene-Therapy-Types.aspx Gene Therapy and Ethics Cultural evolution Cultural evolution is the rapid changes in a population as a result of transmission of knowledge, in contrast to biological evolution, which requires a long time. Biological evolution: This is a process of change of a species under the influence of natural selection and requiring much longer time periods than so-called cultural evolution Technological evolution Technological evolution is the progressive development over time of technologies giving greater human control over the environment. Cultural evolution and biological evolution are closely linked which this relationship is called bio cultural evolution. Biological evolution makes culture possible with the process of change in members of a species that create a culture, which influences the direction of evolution. In culture, involves Human technology where an example of this is new drugs coming out of western nations have drastically changed the makeup of certain African tribes in West Africa (including increasing the lifespan of the population).
Humans intervene so it can benefit themselves and there are many reasons for this, such as;
- For a profit,
- Medical advantages,
- Food production,
- Aesthetics (Cloning), e.t.c...

The first therapeutic human gene therapy clinical trial was approved in 1990 and involved two children suffering from a form of severe combined immunodeficiency (SCID). Gene therapy has a huge potential to be used to treat cancer, AIDS, and genetic diseases, The two basic methods of gene therapy are in vivo and ex vivo gene therapy. In the United States the Recombinant DNA Advisory Committee of the National Institutes of Health oversees gene therapy experiments. Currently, gene therapy trials have been performed in around 30 countries from all over the world. Recent successes in genetics have given many scientists firm belief that gene therapy will be of vital importance in future medical science. The most common approach used in gene therapy is insertion of the normal gene into a nonspecific location within the genome to replace a nonfunctional gene. Types of Gene Therapy... ■There are 2 different of gene therapy such as somatic Gene Therapy and Germ line Gene Therapy. Somatic Gene Therapy is gene therapy conducted in the somatic cells of a patient and Germ line gene therapy is conducted cells, such as eggs or sperm, and are modified. This change is hereditary with the ability to pass on to future generations. Because of the fast technological age, we now have a new advance in the way we function in the world today. We are now able to cure diseases that were not thought possible to cure years ago, advance in the medical ages, change imperfections, increase profit from produce and farming e.t.c. However, for some it raises questions of morally and ethnicity, with gene therapy too being a subject to this questioning. • Could the use of gene therapy make society less accepting of people who are different?
• Should people be allowed to use gene therapy to enhance basic human traits such as height, intelligence, or athletic ability?
• Who decides which traits are normal and which constitute a disability or disorder?
Is it acceptable for human beings to manipulate human genes?

People believe that gene therapy is 'playing god' and also rises concern to various
different religious groups. Treatments... Treatments for CF include:
Antibiotics- to fight of the infections
Physical Therapy- drain or loosen the mucus
Mucus-thinning drugs
Bronchodilators- use of medications that keep the bronchial tubes open
Oral Enzymes and additional nutrition
Lung Transplant- replace the lungs with a healthy lung
Medications- Pain relievers such as Ibuprofen can slow down the progress of CF in young children
Oxygen Therapy- keeps the level of oxygen normal.
Gene Therapy.
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