GENE REPLACEMENT THERAPY

Get Started. It's Free
or sign up with your email address
Rocket clouds
GENE REPLACEMENT THERAPY by Mind Map: GENE REPLACEMENT THERAPY

1. VIRAL VECTORS

1.1. CHALLENGES

1.1.1. transient/low expression

1.1.2. immune response (to vector or gene)

1.1.3. targeting/delivering to specific tissues/cells

1.1.4. insertional mutagenesis - activate proto-oncogene = induce CANCER

1.2. RETROVIRUS (RNA)

1.2.1. Lentivirus (ex. HIV)

1.2.1.1. most common, efficient

1.2.2. INTEGRATES

1.2.2.1. BOTH dividing & non-dividing cells

1.2.2.2. preferentially into coding regions

1.2.3. 8kb of DNA

1.3. ADENO-ASSOCIATED VIRAL VECTORS

1.3.1. NON-INTEGRATION

1.3.2. stable episome

1.3.2.1. BOTH dividing & non-dividing cells

1.3.2.2. long-term expression

1.3.3. 5kb of DNA

1.3.4. non-pathogenic

2. inserting normal gene into somatic cells to compensate for missing/LOF gene

3. ADA-SCID adenosine-deaminase deficiency

3.1. high adenosine, dAMP, dATP

3.1.1. LYMPHOTOXICITY induces apoptosis of developing thymocytes

3.1.1.1. SCID

3.1.1.1.1. no cell/humoral immunity

3.1.1.1.2. lymphopenia = no T-cells, B-cells, NK-cells

3.1.1.1.3. severe recurrent infections

3.1.1.1.4. death by age 2

3.1.2. induces apoptosis of developing thymocytes

3.2. TREATMENTS

3.2.1. ADA-GENE REPLACEMENT THERAPIES

3.2.1.1. EX-vivo CD34+ stem cells with normal gene

3.2.1.2. approved by EU - working well 100% survival

3.2.2. ENZYME REPLACEMENT

3.2.2.1. PEG-ADA

3.2.2.1.1. $$$

3.2.2.1.2. weekly injections

3.2.2.1.3. loses efficacy over time

3.2.3. STEM CELL TRANSPLANT

3.2.3.1. HLA-sibling

3.2.3.2. most recommended by LIMITED

4. Adrenoleukodystrophy (ALD) FATTY ACID METABOLISM DEFECT

4.1. RARE, X-linked

4.1.1. Childhood cerebral form 35%

4.1.2. Onset boys, ages3-10

4.1.3. disability - death by age 2

4.2. mutation in ABCD1 gene for ALD protein = peroxisomal membrane transporter for very long-chain FAs

4.2.1. VLC-FAs need to be oxidized in peroxisomes to MC-FAs prior to metabolism

4.2.2. accumulation of VLC-FAs in brain =immune response = demyelination

4.2.2.1. neurological deterioation

4.3. adrenal cortex dysfunction

4.3.1. corticosteroid treatment

4.4. TREATMENT

4.4.1. allogenic hematopoietic stem cell transplant

4.4.1.1. effective only in early stages

4.4.1.2. limited availability

4.4.2. LENTI-D gene therapy

4.4.2.1. arrests cerebral demyelination

4.4.2.2. free of disability

4.4.2.3. safe alternative

5. WHY ADA & ALD?

5.1. Stem cells easily adjusted EX VIVO and re-infused

5.2. poor treatment options, poor prognosis

6. GENE - BLOCKING THERAPIES

6.1. ANTISENSE THERAPY

6.1.1. oligonucleotide (DNA/RNA) complementary to mRNA of GOF mutation

6.1.1.1. mRNA degradation

6.1.1.2. translation inhibition

6.1.1.3. splicing modulation

6.1.2. DMD

6.1.2.1. skip exon to produce better dystrophin protein

6.1.3. anti-cancer

6.1.3.1. block expression of oncogenes

6.2. RNA INTERFERENCE (RNAi)

6.2.1. dsRNA complementary to mutant mRNA

6.2.2. incoporated into RISC complexes - targeted for destruction

6.2.3. siRNA-RISC complex is catalytic

6.2.3.1. single complex can destroy many mutant mRNA

6.3. FOR GOF OR DOMINANT NEGATIVE MUTATIONS

6.4. HYPERCHOLESTEREMIA - LDLR unable to remove LDL from plasma

6.4.1. STATINS

6.4.1.1. side effects

6.4.1.2. poor efficacy in some

6.4.2. INCLISIRAN = GENE BLOCKING PCSK9

6.4.2.1. siRNA complementary to PCSK9

6.4.2.1.1. RISC degrades PCSK9

6.4.2.1.2. double stranded RNA - highly stable

6.4.2.2. triantennary GalNAc carbohydrate directs drug specifically to liver

6.4.2.3. increased LDLR for more cholesterol uptake

6.4.2.3.1. decrease cholesterol in plasma

7. GENE EDITING THERAPY

7.1. engineered endonuclease creates double-stranded break in DNA

7.1.1. induces cell repair

7.1.1.1. non-homologous end-joining

7.1.1.2. homology-direct repair

7.1.1.2.1. provide GOOD wildtype template

7.2. CRISPR/CAS9

7.2.1. MECHANISM

7.2.1.1. guide RNA directs nuclease to target DNA

7.2.1.2. Cas9 endonuclease creates double stranded break

7.2.2. EITHER NHEJ OR HDR

7.2.2.1. NHEJ

7.2.2.1.1. Knock-out gene of interest

7.2.2.1.2. restore out-of-frame transcript

7.2.2.2. HDR

7.2.2.2.1. correct gene with desired copy of gene

7.2.3. sickle-cell anemia, beta-thalassemia