Topic Stem Cell and Gene Therapy Essay - Main Points!

Q) Discuss the limitation of gene therapy

Main points
Key idea:	Limitation (1) Target cells
· Difficult to introduce normal gene into correct target cells + integrate normal gene into correct chromosome · Target cells may also be non-dividing + have short life-span
Key idea:	Limitation (2) Incorrect insertion of gene
· Incorrect insertion of gene into a proto-oncogene or tumour suppressor gene · Result: gene mutation, may lead to cancer dev
Key idea:	Limitation (3) Level of gene expression
· Even if gene is correctly integrated into chrom, diff to control level of gene expression · Often, expression of gene is too low to produce sig amount of functional proteins
Key idea:	Limitation (4) Constant risk to patients
· Treatment is short-lived, so patients freq treatment · Hence, constant exposure to risk of treatment
Key idea:	Limitation (5) Disadv of viral delivery sys
· Risk of inducing an immune / allergic response to virus · Virus vector may even regain its virulence in body of patient
Key idea:	Limitation (6) Suitable vector & low transfection efficiency of liposomes
· Lack of suitable vector for a large gene, general low transfection efficiency using liposomes as delivery sys
Key idea:	Limitation (7) Not feasible for complex genetic diseases
· Currently, gene therapy is not useful for complex genetic diseases caused by many defective genes · Reason: diff to introduce many genes into same target cells, at same time
Comments: (i) Visualize the answer with the aid of a labelled diagram. (ii) Verbalize the answer + write down the main points w/o referring to the answer (use abbreviations) (iii) Read again within the next 24h & once more within 72h (do not spend more than 10min) (iv) Do not discuss ethical or social issues in the answer. (v) Transfection is a process that introduce nucleic acids through non-viral methods into eukaryotic cells. It is similar to bacterial transformation which is the uptake of foreign DNA into the bacteria.