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These slide include gene therapy defines with their types like Germ line gene therapy,Somatic gene therapy.
with Need of Gene therapy
strategies of gene therapy
Methods of Gene transfer & with
GENE THERAPY FOR INHERITED DISORDERS
WHAT IS GENE THERAPY ?
• Gene therapy is the insertion of genes into an
individual’s cells and tissues to treat A
disease, such as A hereditary disease in which
A deleterious mutant allele is replaced with A
TYPES OF GENE THERAPY
Germ line gene therapy
• In this case, germ cells, i.E., Sperm or eggs are modified by the
introduction of functional genes, which are integrated into their
•The change due to therapy would be heritable n would be
passed on later generation.
Somatic gene therapy
• In this, therapeutic genes are transferred into the somatic
cells of a patient.
•Any modification and effects will be restricted to the individual
patient only, & will not be inherited.
NEED OF GENE THERAPY
• To overcome the disease.
• Targeting the cells of diseased tissues.
• Genes can be inserted into the cells of
patients by direct and indirect routes, and
the inserted genes can integrate into the
chromosomes or remain extra
STRATEGIES OF GENE THERAPY
•Gene augmentation therapy (GAT).
• Targeted killing of specific cells.
• Targeted mutation correction.
• Targeted inhibition of gene expression.
GENE AUGMENTATION THERAPY
• For diseases caused by loss of function of a
gene, introducing extra copies of the normal
gene may increase the amount of normal gene
product to a level where the normal phenotype is
• Targeted to clinical disorders where the
pathogenesis is reversible.
• Applied to autosomal recessive disorders.
NORMAL PHENOTYPE (increase in gene X product)
TARGETED KILLING OF SPECIFIC CELLS
• Popular in cancer gene therapies.
• Genes are directed to the target cells and then
expressed to cause cell killing.
• Direct cell killing – inserted gene are expressed
to produce a lethal toxin or a gene encoding a
prodrug is inserted, conferring susceptibility to
killing by a subsequently administered drug.
DIRECT KILLING OF DISEASE CELLS
CELLS KILLED BY EXPRESSED TOXIN
CELLS KILLED BY DRUG
TARGETED MUTATION CORRECTION
• It can be done at different level:
• At gene level, based on homologous
• At rna transcript level, by using particular types
• of therapeutic ribozymes.
TARGETED GENE MUTATION CORRECTION
DISEASE CELLS (mutant gene X)
NORMAL PHENOTYPE (genetic
mutation corrected to restore
TARGETED INHIBITION OF GENE
• If diseases cells display an inappropriate
expression of a gene (in case of many
cancers), a variety of different system can
be used specifically to block the expression
of a single gene at the DNA,RNA or
Disease cells containing
mutant or harmful gene
Block of expression
of pathogenic gene
METHODS OF GENE TRANSFER
• VIRAL METHODS
• RETROVIRUS VECTORS
• ADENOVIRUS VECTOR
• HERPES SIMPLEX VECTORS
• NON VIRAL METHOD
• BY OLIGONUCLEOTIDES
• BY LIPOSOME
Retroviruses are used for Gene Therapy
LTR gag pol env LTR
10 KB in size
virus containing gene X,
pseudotyped with selected
GENE THERAPY FOR INHERITED DISORDERS
• Recessively inherited disorders are
conceptually the easiest inherited disorders to
treat by gene therapy.
• The first apparently successful gene therapy
was initiated in 1990 for adenosine deaminase
• Cystic fibrosis.
• Familial hypercholesterolemia (fh).
• Gaucher’s diseases
• For neoplastic disorders & infectious disease
GENE THERAPY SUCCESSES AND FAILURES
SCID is often called "bubble boy
disease". SCID became widely known
during the 1970's and 80's, when the
world learned of David Vetter, a boy
with X-linked SCID, who lived for 12
years in a plastic, germ-free bubble.
He died after a bone marrow
A recessive disorder of a mutation in the adenosine
deaminase (ADA) gene causes SCID. Gene therapy
successfully replaced this gene in several ADA patients
GENE THERAPY TRIALS FOR INHERITED
• DISORDER CELLS ALTERED GENE THERAPY STRATEGY
ADA DEFICIENCY T-CELLS & HEMOPOITIC STEM CELLS EX VIVO GAT USING RECOMBIN-ANT
AN ADA GENE.
CYSTIC FIBROSIS RESPIRATORY EPITHELIUM IN VIVO GAT USING RECOMBIN-ANT
ADENOVIRUSES OR LIPOSOME-TO
DELIVER THE CFTR GENE
FAMILIAL LIVER CELLS EX VIVO GAT USING RETROVIRUS
HYPERCHOLESTEMIA TO DELIVER THE LDL RECEPTOR
GAUCHER’S DISEASE HEMOPOITIC STEM CELLS EX VIVO GAT USING RETROVIRU-SES
TO DELIVER THE GLUCO-CEREBROSIDASE
PROBLEMS AND ETHICS
• SHORT-LIVED NATURE OF GENE
• IMMUNE RESPONSE.
• PROBLEMS WITH VIRAL VECTORS.
• CHANCE OF INDUCING A TUMOR.
• It is believed that gene therapy will revolutionize the
practice of medicine. This technique has the ability to
cure many of the diseases that have effected our
society for years i.E. People that have serious genetic
• As scientist discover more genes & their functions,
the potential for this treatment is limitless. As we
know our fate is indeed in our gene.
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