gene therapy Flashcards
what is gene therapy
using genes to treat or prevent disease
-inserting functional allele of particular gene into cell that contains mutated or non-functional allele of that gene
what is somatic cell gene therapy and what can be treated
alterations made to patients genome only affecting somatic (body) cells
can be used to treat recessive genetic disorders e.g cystic fibrosis but not inherited to offspring
what causes cystic fibrosis, what does the CFTR gene code for and what is the function of the protein
symptoms of cystic fibrosis?
-caused by inheritance of 2 recessive alleles for CF- lacking CFTR functional gene
-codes for chloride ion channels which let CL- to diffuse out of epithelial cells, water following to keep membranes moist= CF not moist
-thick mucus lining lungs= bacterial infections, breathing dificulties, low body weight due to difficulty with digestion, salty sweat
explain how gene therapy can be used to treat cystic fibrosis
copies of DNA for normal allele inserted into loops of DNA which then attach to liposomes= sprayed as an aerosol, DNA is then taken up by some cells lining airways
which gene is defective in severe combined immunodeficiency disease (SCID) and how can gene therapy be used to treat it
-ADA enzyme making gene
-normal ADA gene isolated using restriction endonuclease
-ADA gene inserted into a retrovirus
-retroviruses containing ADA gene mixed with patient’s bone marrow cells
-retrovirus injects copy of normal ADA gene into bone marrow cells
-bone marrow re-introtuced into patients blood to give genetic code to make ADA
how could a virus be used as a vector in gene therapy
using genetically modified virus that normally infects humans
what are problems with using viral vectors to carry genes into cells
-may cause immune/ inflammatory response
-patient may become immune to virus
-can’t control where virus inserts allele, may disrupt gene involved in regulating cell division
-disrupts regulation of expression of other genes
what is an artificial chromosome
constructing artificial chromosome to exist along the 46 chromosomes
what is germ line gene therapy and why is it viewed as being ethically unacceptable
-involves altering genome of gametes or zygote
-no consent from zygote was given
what are the differences between germ line gene therapy and somatic cell gene therapy
somatic:
-body cells
-can’t be inherited
-short lived
-only some cells have gene
germ line:
-gametes
-can be inherited
-long lived
-all cells have gene
what are some issues with somatic
somatic:
-Insertion of functioning allele of gene into target cells may require removal of cells followed by treatment and reintroduction (ex vivo therapy)
-Treatment is short-lived so needs to be repeated regularly as specialised cells are may not divide and will not pass on the inserted allele
-The functioning allele may not be expressed requiring the need for vectors but - cells become immune when virus vectors are used more than once and liposome vectors are inefficient
-Gene therapy is restricted to the patient - the faulty allele may still be inherited by offspring
what are some issues and benefits with germ line therapy
-Insertion of functioning allele of gene is more straightforward as it is put into germ line cells e.g. embryonic stem cells
-All cells derived from the germ line cells contain the functioning allele and may pass it on to any offspring
-Unethical to engineer human embryos. The inserted allele may undergo changes which could damage the embryo
-This type of gene therapy could also be passed on to and ‘cure’ offspring
