About Gene therapy

1. Gene Therapy
Submitted By-
Amit Kumar Sahoo
15151

3. WHAT IS GENE THERAPY ?
• Definition: an experimental technique for correcting defective
genes that are responsible for disease development
• The most common form of gene therapy involves inserting a
normal gene to replace an abnormal gene
• Other approaches used:
 Replacing a mutated gene that causes disease with a
healthy copy of the gene.
 Inactivating, or “knocking out,” a mutated gene that is
functioning improperly.
 Introducing a new gene into the body to help fight a

4. HISTORY AND DEVELOPMENT
OF GENE THERAPY
• 1960: The concepts of Gene Therapy was introduced
• 1970: Friedmann and Roblin author of a paper in Science titled "Gene therapy for human
genetic disease?” cite the first attempt to perform gene therapy
• 1990:
 The first approved gene therapy case at the National Institute of Health, U.K. It was
performed on a four year old girl named Ashanti DaSilva. It was a treatment for a
genetic defect that left her with an immune system deficiency
 New gene therapy approach repairs errors in messenger RNA derived from defective
genes. This technique has the potential to treat the blood disorder Thalassaemia,
Cystic fibrosis, and some cancers
 Sickle cell disease is successfully treated in mice

5. • 2006: Scientists at the National Institutes of Health (Bethesda,
Maryland) have successfully treated metastatic melanoma in two
patients. This study constitutes one of the first demonstrations that
gene therapy can be effective in treating cancer.
• 2007- 2011: Research is still ongoing and the number of diseases that
has been treated successfully by gene therapy increases.
Retinal disease
Colour blindness
Adrenoleukodystrophy
• 2011: Medical community accepted that it can cure HIV as in 2008,
Gero Hutter has cured a man from HIV using gene therapy

7. GERM LINE GENE THERAPY
• Result in permanent changes.
• Potential for offering a permanent therapeutic effect for all who inherit
the target gene.
• Possibility of eliminating some diseases from a particular family.
• Also raises controversy:
 Some people view this type of therapy as unnatural, and liken it to
"playing God”.
 Others have concerns about the technical aspects.

9. SOMATIC GENE THERAPY
• Affects only the targeted cells in the patient, and is not passed to
future generations.
• Short-lived because the cells of most tissues ultimately die and are
replaced by new cells.
• Transporting the gene to the target cells or tissue is also
problematic.
• Appropriate and acceptable for many disorders, including cystic
fibrosis, muscular dystrophy, cancer, and certain infectious
diseases.

10. Types of somatic gene therapy

12. In vivo gene therapy
• 1. The genetic material is transferred directly into the body of the
patient
• 2. More or less random process; small ability to control; less
manipulations
Ex vivo gene therapy
1.The genetic material is first transferred into the cells grown in vitro
2. Controlled process; Genetically altered cells are selected and expanded; more
manipulations
3. Cells are then returned back to the patient

13. BASIC PROCESS OF GENE THERAPY
1. VIRAL VECTOR
2. NON VIRAL VECTOR
• The two major classes of methods :
recombinant viruses – VIRAL VECTOR
naked DNA or DNA complexes – NONVIRAL VECTOR

14. Why VIRAL VECTOR?
• Virus bind to their hosts and introduce their genetic material into
the host cell.
• Plausible strategy for gene therapy, by removing the viral DNA and
using the virus as a vehicle to deliver the therapeutic DNA.
• The viruses used are altered to make them safe, although some risks
still exist with gene therapy.

16. http://en.wikipedia.org/wiki/Gene_therapy

17. NON VIRAL VECTOR
• Methods of non-viral gene delivery have also been explored using
physical (carrier-free gene delivery) and
• chemical approaches (synthetic vector-based gene delivery).
• Physical approaches, including
Needle injection
Electroporation
Gene gun
Ultrasound
Hydrodynamic delivery
employ a physical force that permeates the cell membrane and facilitates
intracellular gene transfer
CHEMICAL METHODS (THAT ENHANCE THE DELIVERY OF GENE THERAPY)
-lipoplexes &
-polyplexes

18. Injections of naked DNA
http://en.wikipedia.org/wiki/Gene_therapy-1

19. Current attempts with naked DNA vaccination
in infectious diseases

20. Ballistic DNA Injection (gene guns)
• Invented for DNA transfer to plant
cells
• Fully applicable to eukaryotic cells
plasmid DNA shown here

21. Liposomes
Next level idea – why naked DNA?
Lets’ wrap it in something safe
to increase transfection rate
Lipids – are an obvious idea !
Therapeutic drugs

22. DNA delivery of genes by liposomes
Cheaper than viruses
No immune response
Especially good for in-lung delivery (cystic
fibrosis)
100-1000 times more plasmid DNA needed
for the same transfer efficiency as for viral
vector

23. SUCCESS CASES OF GENE THERAPHY
Blindness
Parkinson’s
Disease

24. GENE THERAPY CURES BLINDNESS
• Cure blindness of inherited condition
• Leber’s conginetal amaurosis
- inherited disease caused by an abnormality in a
gene called RPE65.
- The condition appears at birth or in the first few
months of life and causes progressive worse and
loss of vision.

25. HOW IT WORKS??
• used harmless viruses
• enable access to the cells beneath the retinas of patients
• By using a very fine needle
-safe in an extremely fragile tissue and can improve vision in a
condition previously considered wholly untreatable.

26. GENETHERAPYREDUCESPARKINSON’SDISEASE
SYMPTOMS
• it significantly improved the weakness of the symptoms such as
tremors, motor skill problems, and rigidity
• Main- overactive brain region: the subthalamic nucleus should be
introduced with gene
• that would produce GABA—an inhibitory chemical—then they could
potentially quiet that brain region and alleviate tremors.

27. HOW IT WORKS??
• Done with local anesthesia, used a harmless, inactive virus
[AAV-2 GAD]
• Deliver the GAD gene into patient’s subthalamic nucleus
• The gene instructs cells to begin making GABA
neurotransmitters to re-establish the normal chemical balance
that becomes dysfunctional as the disease progresses

28. ADVANTAGES OF GENE THERAPY
• Give a chance of a normal life to baby born with genetic disease.
• Give hope of healthy life to cancer patient.
• For certain disease that do not have any cure except gene therapy, it
could save many lives

29. DISADVANTAGES OF GENE THERAPY
• The genetic testing, screening and research in finding the availability of
certain gene is very controversy.
• May increase rate of abortion if prenatal test regarding baby with genetic
disease is done.
• The cost is very high and the patient might need an insurance to cover the
treatment.
• Cosmetic industry may monopolized this gene therapy if it is used in
enhancing beauty and in vanishing the aging effect, rather than used for
treatment of a disease.

30. References
• ghr.nlm.nih.gov › Handbook › Gene Therapy
• learn.genetics.utah.edu/content/genetherapy/gtintro/
• www.yourgenome.org/facts/what-is-gene-therapy
• www.asgct.org › General Public › Educational Resources

31. http://www.wellesley.edu/Biology/Courses/219/Gen_news/i3_Gene_Therapy.jpg