By: Sudeshna Dighe, Varun Doshi, Rahul Jadhav
What is a gene?
- It is a basic unit of heredity, which are carried on a chromosome they encode how to make a protein (DNAàRNA àproteins).
- When altered causes dysfunction of a protein. When there is a mutation in the gene, then it will change the codon, which will change which amino acid that will lead to change in the conformation of protein and lead to disfunctioning of protein.
- Genetic disorders result from mutations in the genome.
What is Gene Therapy?
It is a technique for correcting defective genes that are responsible for disease development
There are four approaches of Gene Therapy:
- A normal gene inserted to compensate for a nonfunctional gene
- An abnormal gene traded for a normal gene
- An abnormal gene repaired through selective reverse mutation
- Change the regulation of gene pairs
Gene therapy may be classified into the two following types
Germ line gene therapy
- In the case of germ line gene therapy, germ cells, i.e., sperm or eggs are modified by the introduction of functional genes, which are ordinarily integrated into their genomes.
- Therefore, the change due to therapy would be heritable and would be passed on to later generations. This new approach, theoretically, should be highly effective in counteracting genetic disorders and hereditary diseases. However, many jurisdictions prohibit this for application in human beings, at least for the present, for a variety of technical and ethical reasons.
- In the case of somatic gene therapy, the therapeutic genes are transferred into the somatic cells of a patient. Any modifications and effects will be restricted to the individual patient only, and will not be inherited by the patient’s offspring or later generations.
Somatic gene therapy
History of Gene therapy:
In the 1980s, Scientists began to look into gene therapy. They would insert human genes into a bacteria cell. Then the bacteria cell would transcribe and translate the information into a protein. Then they would introduce the protein into human cells
First case of Gene therapy:
The first gene therapy was performed on September 14th 1990, Ashanti De Silva was treated for SCID ( Severe combined immunodeficiency )Doctors removed her white blood cells, inserted the missing gene into the WBC, and then put them back into her blood stream. This strengthened her immune system. Only worked for a few months.
How it works ?
- 1. A vector delivers the therapeutic gene into a patient’s target cell
2. The target cells become infected with the viral vector
3. The vector’s genetic material is inserted into the target cell
- Functional proteins are created from the therapeutic gene causing the cell to return to a normal state
- Replicate by inserting their DNA into a host cell
- Gene therapy can use this to insert genes that encode for a desired protein to create the desired trait
Types of Viruses
- Adeno-associated Viruses
- Adeno-associated Viruses
- 1. Adeno-associated Viruses– Adeno-associated Virus- small, single stranded DNA
that insert genetic material at a specific point on chromosome 19. From parvovirus family- causes no known disease and doesn’t trigger patient immune response. It has low information capacity. A gene is always “on” so the protein is always being expressed, possibly even in instances when it isn’t needed. Hemophilia treatments, for example, a gene-carrying vector could be injected into a muscle, prompting the muscle cells to produce Factor IX and thus prevent bleeding.
- 2. Retroviruses– It is created by double stranded DNA copies from RNA. The
retrovirus goes through reverse transcription using reverse transcriptase and RNA the double stranded viral genome integrates into the human genome using integrase, it inserts the gene anywhere because it has no specific site it may cause insertional mutagenesis. Vectors used are derived from the human immunodeficiency virus (HIV) and are being evaluated for safety.
- 3. Adenoviruses- Are double stranded DNA genome that cause respiratory,
intestinal, and eye infections in humans. The inserted DNA is