The document discusses genes and genetic disorders. It defines a gene as the basic physical and functional unit of heredity, and notes that genes are segments of DNA that code for specific traits. Genetic disorders are caused by variations or mutations in genes. The document then discusses recent discoveries in epigenetics, gene marking, and gene therapy. Gene therapy involves introducing new genes into cells to treat diseases, either by replacing defective genes, inactivating abnormal genes, or introducing new genes to fight diseases. Various gene therapy approaches and vectors, including viral vectors like retroviruses and adenoviruses, are described.

1. ANUPAM DWIVEDI
17RTM2606
REGULATORY TOXICOLOGY
NIPER SAS NAGAR

2. GENE
 Gene was coined by W Johansen in 1909
 The gene is to genetics what the atom is to chemistry
 The gene is the unit of genetic information that controls a
specific aspect of the phenotype
 genes are the fractions or part of DNA molecule which
regarded as the genetic material
 Genes can be transmitted from parent to off springs
 The HGP has estimated that human have between 20,000-
25,000 genes

3. Contd...
T.M Morgan proposed the
gene theory which state that:
 Chromosomes are bearers
of hereditary units and each
chromosome carries
hundreds or thousands of
genes
 The genes are arranged on
the chromosomes in the
linear order and on the
special regions or locus

4. Contd...

5. WHAT ARE GENETIC DISORDERS?
Genetic disorder is a disease caused by a "variation" or
"mutation“ of a gene
 Genetic disorders can be passed on to family members
who inherit the genetic abnormality
 A small number of rare disorders are caused by a
mistake in a single gene
Most disorders involving genetic factors, such as heart
disease and most cancers, arise from a interplay of
multiple genetic changes and environmental factors

6. Recent Discoveries
THE
 EPIGENOME
 GENE MARKING
 GENE THERAPY

7. EPIGENOME
 An epigenome consists of a record of the chemical changes to
the DNA and histone proteins of an organism; these changes
can be passed down to an organism's offspring
 Changes to the epigenome can result in changes to the
structure of chromatin and changes to the function of the
genome
 The epigenome is a multitude of chemical compounds that
can tell the genome what to do
 DNA holds the instructions for building the proteins that carry
out a variety of functions in a cell.
 They can attach to DNA and direct such actions as turning
genes on or off, controlling the production of proteins in
particular cells

8. GENE MARKING
• Attachment of Epigenomic compounds to DNA
• “Unchanged DNA sequence” but “Changed DNA
instructions”
• The marks are sometimes passed on from cell to cell as
cells divide
• They can “switch ON or OFF the genes” followed by
uncontrolled growth of cells

9. GENE THERAPY
Gene therapy is the introduction of genes into
existing cells to prevent or cure a wide range of
diseases
Gene therapy is a novel treatment method which
utilizes gene as therapeutic molecules instead of
conventional drug
It is a technique for correcting defective genes
responsible for disease development
Gene therapy is defined as a set of strategies that
modify the expression of an individual’s or that
correct abnormal genes
Each strategies involves the administration of a
specific DNA or RNA

10. Contd...
In gene therapy, DNA encoding a therapeutic
protein is packaged within a vector which transports
the DNA inside cells within the body
The disease is treated with minimal toxicity by the
expression of the inserted DNA by the cell
machinery.

11. HISTORY OF GENE THERAPY
1960
The concepts of Gene
Therapy was introduced
1972
Friedman and Roblin
authored a paper in Science
titled "Gene therapy for human
genetic disease”
1984
A retrovirus vector system was
designed that could efficiently
insert foreign genes into
mammalian chromosomes

12. Contd...
1990: Gene Therapy not a fantasy now…..
• The first approved gene therapy in
the US took place on 14
September 1990, at the National
Institutes of Health (NIH) under
the direction of William French
Anderson
• In 1990, a 4 year old girl named
Ashanti DeSilva was the first
patient to receive gene therapy for
SCID (severe combined
immunodeficiency)
Ashanti DeSilva

13. Contd...
1992
Doctor Claudio Bordignon performed
the first procedure of gene therapy
using hematopoietic stem cells as
vectors to deliver genes intended to
correct hereditary diseases
1999
Death of Jesse Gelsinger in a
gene-therapy experiment
2003
a research team inserted genes into
the brain for the first time. They
used liposomes which, unlike viral
vectors, are small enough to cross
the blood–brain barrier

14. Contd...
2006
successful use of gene therapy
to treat two adult patients for
X-linked chronic granulomatous
disease
2007
first gene therapy trial for
inherited retinal disease
2010
an 18 year old male patient in
France with beta- thalasemia
major had been successfully
treated

15. Contd...
2011
Medical community accepted
that it can cure HIV as in 2008,
Gero Hutter has cured a man
from HIV using gene therapy
2011-2015
Research is still ongoing and
the number of diseases that
has been treated successfully
by gene therapy increases

16. TYPES OF GENE THERAPY
1. SOMATIC CELL
GENE THERAPY
2. GERM LINE
GENE THERAPY

17. SOMATIC CELL GENE
THERAPY
GERM LINE GENE
THERAPY
Therapeutic genes transferred into
the somatic cells
Therapeutic genes transferred into
the germ cells
E.g.. Introduction of genes into
bone marrow cells, blood cells,
skin cells etc
E.g.. Genes introduced into eggs and
sperms
Will not be inherited later
generations
It is heritable and passed on to
later generations
At present all researches directed to
correct genetic defects in somatic cells
For safety, ethical and technical
reasons, it is not being attempted at
present

18. SOMATIC CELL GENE THERAPY
single defective cell taken out of an individual’s
body
 functional version of gene introduced into cell in
a laboratory
 cells reproduce
 copies of cells with a corrected version of the
gene is injected back into the patient
the good gene ends with the patient and is not
inherited by their offspring

19. TYPES OF SOMATIC CELL GENE
THERAPY
 IN VIVO GENE THERAPY: delivery of new genetic
material directly to target cells within the body
 The challenge lies in ensuring the specificity
and in reaching the correct target cells within the
body
 EX VIVO THERAPY: target cells are removed from
the body and then genetically modified
 The cells are then returned to the body after
selection and amplification
 This is a safe method but dependent on the
type of cells being targeted

21. EXAMPLE OF IN VIVO GENE
THERAPY
In patients with cystic fibrosis, a protein called
cystic fibrosis trans-membrane regulator (CFTR)
is absent due to a gene defect
In the absence of CFTR chloride ions concentrate
within the cells and it draws water from
surrounding
 This leads to the accumulation of sticky mucous
in respiratory tract and lungs.
Treated by in vivo replacement of defective gene
by adenovirus vector

23. EXAMPLE OF EX VIVO GENE
THERAPY
1st gene therapy – to correct deficiency of
enzyme, Adenosine deaminase (ADA)
Performed on a 4yr old girl Ashanthi DeSilva
Was suffering from SCID- Severe Combined
Immunodeficiency
Caused due to defect in gene coding for ADA
 Deoxyadenosine accumulate and destroys T
lymphocytes
Disrupts immunity , suffer from infectious
diseases and die at young age

24. GERM LINE GENE THERAPY
normal version of gene is inserted into germ
cells
 those germ cells will divide normal versions
of the gene
 any zygote produced as a result of this germ
cell will have a correct version of the defective
gene and will continue passing it on to their
offspring

25. APPROACHES TO GENE THERAPY
Several approaches to gene therapy are being
tested, including:
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 disease

26. VECTORS IN GENE THERAPY
 In general, a gene cannot be directly inserted into a person’s
cell. It must be delivered to the cell using a carrier, or vector.
 Vectors are carrier molecules which are employed to enhance
gene transfer efficiency in gene therapy. In optimizing a
particular vector, one must consider:
– Host immune response
– Must target specific tissues for long term gen expression
– Regulation of the gene after insertion
 Vector systems can be divided into:
1. Viral vectors
2. Non-viral vectors

27. VIRAL VECTORS NON VIRAL SYSTEMS
Retroviruses Gene gun methods
Adeno viruses Plasmid liposome
complex
Adeno associated viruses Spontaneous uptake by
endocytosis
Herpes simplex viruses Microinjections

28. RETROVIRUS VECTOR SYSTEM
The recombinant retroviruses have the ability
to integrate into the host genome in a stable
fashion
Can carry a DNA of size – less than 3.4kb
Replication defective virus particles
Target cell - dividing

29. ADENO VIRUSES
 These are DNA viruses
 These do not produce serious illness so are used for gene therapy
 The genes of the virus are removed so they lose the ability to
divide
 The human genes are inserted and the vector is transfected in the
culture containing the sequences for replication
 The virus thus replicates in the cell culture
 The packed viruses are then introduced in to the patient

30. • Adeno associated virus-
It is also DNA virus. It has no known
pathogenic effect and has wide tissue affinity.
It integrates at a specific site
• Herpes simplex virus-
This is a disabled single copy virus and has
defective glycoprotein. When propagated in
the complementary cells, viral particles are
generated. Since they can replicate only once
so there is no risk of a disease
ADENO ASSOCIATED VIRUS AND
HERPES SIMPLEX VIRUS

31. NON VIRAL APPROACH- LIPOSOMES
Target cell
DNA-liposome complex is taken into
the target cell by endocytosis
The liposome is degraded within the
endosome and the DNA is released into
the cytosol
The DNA is imported into the cell nucleus
Liposome
DNA carrying the
gene of interest
Endosome
By recombination, the DNA carrying
the gene of interest is integrated into
a chromosome of the target cell
Integrated
gene

32. RECENT ADEVANCEMENT IN GENE
THERAPY
 On 20th of March 2018, a 13-year-old boy from New Jersey
became the first person in the US to receive an FDA-approved
gene therapy for an inherited disease. The therapy, Luxturna,
from Spark Therepeutics, was approved by the FDA in
December to treat a rare, inherited form of blindness
 On 16th of Oct 2017, Food and Drug Administration approved
a promising new treatment, made by Gilead Sciences, Called
CAR-T. Gilead’s treatment, to be sold as Yescarta, is the
second CAR-T to win FDA approval

33. Contd...
 In Aug 2014, FDA approved a drug Kymriah, first even gene
therapy available for treatment of children with a form of
acute lymphoblastic leukemia (ALL)
 The marketing authorization of Glybera and Strimvelis by the
European Medicines Agency (EMA) marked the end of the
long and often troubled road of gene therapy from biological
concept to medical practice. Glybera is a recombinant adeno-
associated virus (AAV) vector designed for gene therapy of
lipoprotein lipase deficiency, while Strimvelis is a genetically
modified hematopoietic stem cell preparation for the
treatment of severe combined immunodeficiency (SCID)

34. Contd...
• A gene therapy called NLX-P101 dramatically
reduces movement impairment in Parkinson's
patients, according to results of a Phase 2
study published on March, 2011 in the journal
Lancet Neurology

35. ADVANTAGES OF GENE THERAPY
Gene therapy has the potential to eliminate
and prevent hereditary diseases such as cystic
fibrosis, ADA- SCID etc
It is a possible cure for heart disease, AIDS and
cancer
It gives someone born with a genetic disease a
chance to life
It can be used to eradicate diseases from the
future generations

36. DISADVANTAGES OF GENE THERAPY
Long lasting therapy is not achieved by gene
therapy due to rapid dividing of cells, benefits of
gene therapy is short lived
Immune response to the transferred gene
stimulates a potential risk to gene therapy
Viruses used as vectors for gene transfer may
cause toxicity, immune responses, and
inflammatory reactions in the host
Disorders caused by defects in multiple genes
cannot be treated effectively using gene therapy

37. ETHICAL ISSUES
Who will have access to therapy?
 Is it interfering with God’s plan?
 Should people be allowed to use
gene therapy to enhance basic
human traits such as height,
intelligence etc.?
 Is it alright to use the therapy in
the prenatal stage of development
in babies?
 GENE DOPING

38. GENE THERAPY AND REGULATORY
AFFAIRS
Regulatory and ethical issues of gene transfer
are usually a secondary preoccupation of
researchers. Conducting gene therapy clinical
trials with genetically modified organisms as
the vectors presents unique safety and
infection control issues. The area is governed
by a range of legislation and guidelines:
 Recombinant DNA Advisory Committee (RDAC)
 Center for Biologics Evaluation and Research (FDA
- CBER)
 European Union - Biotechnology (EU)
 The European Medicines Agency (EMA)
 Gene Therapy Discussion Group of The
International Conference on Harmonisation(ICH)

39. CONCLUSION
 The potential use of this therapy to cure other more
complicated diseases, such as cancer and coronary diseases,
also seems promising. Gene therapy is still in its infancy, but it
is believed that as it matures, it will become an effective
treatment for the myriad of genetic diseases that affect
humanity
 Theoretically, gene therapy is the permanent solution for
genetic diseases but it has several complexities, At its current
stage, it is not accessible to most people due to its huge cost

40. Will gene therapy make humans
masters of own evolution?
Thank