Treatments of genetic disease (24)

Question 1

What do pharmacological chaperones do?

Answer 1

• misfolded proteins are normally degraded in the ER
• chaperones are small molecules that correct protein mis-folding
• mutation specific
  e. g. Migalastat stabilises enzyme in correct shape for Fabry disease

Question 2

What do pharmacological modulators do?

Answer 2

• receptor agonists/antagonists
• ion channel activators/blockers
• act on mutant receptors/channels
  e. g. Bcl-abl Kinase inhibitors only bind to mutant form of kinase
• can be used in combination w/ chaperones e.g. CF

Question 3

What do amino glycoside antibiotics do?

Answer 3

• bind to bacterial ribosome
• cause mistranslation of premature stop codons
• drugs based on these can read through non-sense mutations
  e. g. Ataluren for DMD- read through premature stop codon

Question 4

How does mitochondrially inherited disease therapy work?

‘3-parent baby’

Answer 4

• take DNA from mother’s egg and transfer to donor egg, so normal mitochondria (from donor)
• requires IVF

Question 5

How does virus gene therapy work?

Answer 5

• engineer virus to carry a therapeutic gene
• choose appropriate virus depending on target tissue: AAV, adenovirus, lentivirus, vaccinia
• inserting relevant gene into viral genome, so gets integrated into ours

Question 6

How does in vitro gene therapy CAR-T cell work?

Answer 6

• only effective against certain lymphomas
• isolate patient T cells, insert gene for Chimeric Antigen Receptor using lentivirus–> expand CAR-T cells and reinfuse into patient
• sticks an antibody fragment on–> become higher affinity TCRs that recognise cancer cell antigen directly

Question 7

How does in vivo therapy supplement work?

Answer 7

• replacing defective copy of a gene
• using a virus to carry in a working copy of a functional gene that someone lacks
• usually inject locally: eye (e.g. Luxturna rAAV2 expressing RPE65), spine, brain

Question 8

How does antisense oligonucleotide treatment work?

Answer 8

• based on antisense oligonucleotides: short, modified nucleic acids complementary to target–> bind to target and block translation OR bind to pre-mRNA and prevent splicing
• cheap
• impair protein production

Question 9

How does exon skipping work?

Answer 9

• during pre-RNA processing
• oligonucleotides can make a disease-causing exon be skipped
• to put RNA back in reading-frame
• exon skipped must not be vital
• generally only works for large proteins e.g. DMD

Question 10

What is the principle of gene editing with CRISPR-Cas9?

Answer 10

• correct small errors e.g. point mutations
• cannot correct large changes (deletions, triplet expansion…)
• may have off target effects
• same problems as other methods: getting into cell and targeting

Question 11

What are inborn errors of metabolism?

Answer 11

• largest group of genetic disease
• affect a variety of pathways: carb metabolism, fatty acid metabolism etc…
• lack enzyme, so inc. [substrate] and/or make alternate product–> can both be toxic
• e.g. PKU, MCAD deficiency

Question 12

What are classic treatments of genetic diseases?

Answer 12

• replace a missing enzyme/hormone e.g. haemophilia, GH deficiency
• treatment by diet e.g. low protein
  ^ no need to know gene involved, bc not mutation specific

Question 13

What are the side effects of in vitro gene therapy CAR-T cell?

Answer 13

can cause cytokine release syndrome and neurological damage