MM 27 Gene Therapy

Question 1

Gene Therapy

Answer 1

The modification of genes to prevent, alleviate, or cure disease.

Was originally purposed to cure diseases with a single genetic component. But now is being also purposed for more complex diseases (cardiovascular disease).

Question 2

Gene Supplementation (augmentation)

Answer 2

Addition of a functional copy of of a defective gene. Or, addition of a suicide or prodrug gene to cell.

Question 3

Targeted inhibition of gene expression - 3 types

Answer 3

Silence oncogenes in cancer, silence unwanted immune responses, or silence gain of function genes in inherited diseases.

1: Antisense oligonucleotides
2: Ribozymes
3: siRNA

Question 4

Germ-line gene therapy

Answer 4

Genetic alterations would be heritable. Could cure all monogenic diseases. But leads to ethical concerns.

Question 5

Somatic gene therapy - 2 types

Answer 5

Not heritable. May be stable (integrated into host cell chromosome and transferred to daughter cells) or transient (not integrated into DNA and not passed on to daughter cells).

Question 6

In vivo vs Ex vivo

Answer 6

In vivo: genes transplanted directly into patient.

Ex vivo: Cells removed from patient, modified in vitro, and transplanted back into patient.

Question 7

Antisense oligonucleotides (a targeted inhibition of gene expression)

Answer 7

Single stranded oligonucleotides (15-20 bases in length) placed into cell to prevent translation of mRNA. Hybridized mRNA is also then more vulnerable to degradation by RNAase H.

Question 8

Ribozymes (a targeted inhibition of gene expression)

Answer 8

Ribozymes are RNA molecules that are capable of catalyzing specific biochemical reactions, similar to the action of protein enzymes. The most common activities of natural ribozymes are the cleavage of RNA and DNA and peptide bond formation.

Ribozymes could be introduced with specific sequences intended to recognize and cleave target RNA.

Question 9

RNAi

Answer 9

RNA interference: When cells see double stranded RNA they cleave it, thinking it to be viral or miRNA.

Double stranded RNA could be introduced, which would be cleaved by ribonuclease into siRNA (short interfering). The cell then uses the siRNA to identify complimentary mRNA and degrade it.

This has been more effective than antisense.

Question 10

Gene vector

Answer 10

Delivery system of gene therapeutics to the patient. The two major classes of methods are those that use recombinant viruses and those that use naked DNA or DNA complexes.