MG (Gene Therapy)
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What’s germ line therapy
definition: Gene therapy by inserting functional alleles into gametes or zygotes (illegal in humans) - If successful, all cells of the embryo will contain the corrected gene when cell divides by mitosis (changes entire genetic male up) - permanent and also ensures offspring inherit corrected gene - descendants of patient haven’t given consent - genes inserted may find their way into a location that could disrupt the expression or regulation of other genes or increase the risk of cancer.
what’s somatic cell gene therapy
definition : gene therapy by inserting functional alleles into body cells - any offspring could still inherit the disease. - has to be repeated many times as the effects do not last very long. - Cystic fibrosis (CF) is a genetic disorder that’s very damaging to the respiratory system, so somatic therapy for CF targets the epithelial cells lining lungs.
what’s the principle of gene therapy
• is to insert a functional allele of a particular gene into cells that contain only mutated and non-functioning alleles of that gene. • If the inserted allele is expressed, then the individual will produce a functioning protein and no longer have symptoms associated with the genetic disorder.
How are liposomes used as vectors (small spheres of lipid bilayer)
• Functioning genes isolated from human cells & inserted into plasmids. • Plasmids extracted & wrapped in lipid molecules (forming a liposome). • Liposomes sprayed into patients airways via a nasal aerosol. • Liposomes pass easily through the plasma membrane of cells and nucleus.
How are liposomes used to treat cystic fibrosis?
• alleles packaged in liposomes which are placed into inhaler and sprayed into the nose of patient • some pass through plasma membrane and into the nucleus through (nuclear envelope) of cells lining respiratory tract • CFTR gene inserted into host genome and its expressed into CTRF protein (a Cl- channel)
How are viruses used as vectors?
• GM virus to encase functioning allele inserted into patient • made unable to cause disease • can enter recipient cells
what are potential problems of using viruses as vectors?
• may still cause an immune or inflammatory response in patient • patient may become immune so subsequent deliveries are more difficult • allele inserted into genome in a location that disrupts a gene involved in regulating cell division, increasing risk of cancer • allele inserted in location that disrupts the the regulation of the expression of other genes
what’s the potential of artificial chromosomes in gene therapy
• Research is being carried out into the possibility of inserting genes into an artificial chromosome that would co-exist with the other 46 chromosomes in the target cells.
positives of gene therapy
• Could prolong the lives of people with life-threatening genetic disorders • Could give people with genetic disorders a better quality of life if it helps to ease symptoms • Germ line therapy would allow the carriers of genetic disorders to conceive a baby without that disorder • Germ line therapy could decrease the number of people that suffer from genetic disorders and cancer, which is beneficial for individuals and society as a whole (fewer people will require treatment).
Negatives of gene therapy
• Technology could potentially be used in ways other than for medical treatment, such as for treating the cosmetic effects of ageing. • Concern that gene therapy is expensive - some people believe that health service resources could be better spent on other treatments that have passed clinical trials. • Potential to do more harm than good by using the technology.