genetic testing raeanna illman, john hurlburt, duane goehring, kim silvernale
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Genetic Testing
RaeAnna Illman, John Hurlburt, Duane Goehring, Kim Silvernale
Gene Therapy
• Gene Therapy is delivering replacement genes to correct the problem at it’s source.
Three Phases of Treatment Evolution
• Treating the gene to cure a disease is still not the norm despite HGP advances
•Replacement of missing proteins with material from donors.
•Obtaining pure proteins using recombinant DNA technology.
•Deliver replacement genes
Gene Therapy
• With recent advances, gene therapy has now moved to the treatment of common diseases.
• Gene therapy began by treating complex, uncommon, and inherited diseases.
3 Models for Gene Therapy:
• In-vivo
•Ex-vivo
•In-situ
Germline and Somatic Therapies
• Germline gene therapy alters the DNA of a gamete or fertilized ovum.
• Somatic gene therapy corrects only the cells that an illness affects.
• Picorray therapy places “artificial” genes on a microchip
Methods of Delivery
• Physical – microinjection, particle bombardment, electroporation.
• Chemical – liposomes which secure genetic cargo and can penetrate plasma membranes.
• Biological- Vectors; remove the virus from its membrane and put in its place corrective genes. (very flexible)
Proteins
• Gene therapy uses proteins that are missing to treat the phenotype
• This has mitigated issues with ADA deficiency and white blood cell problems
• A lasting treatment is the alteration of Progenitor cells which make up one in roughly a billion bone marrow cells.
• Potential problems:• Mutations remain in the genotype• Not a dynamic fix which will last throughout the germline• Although the protein is fixed, the gene remains mutated
Setbacks to Gene Therapy
• The body may reject the foreign or altered genes.• Unused amino acids let off a nitrogen gas which mixed
with hydrogen to form ammonia that goes into the bloodstream and then into the brain.
• Method of Transportation = inject unaffected genes into a dead virus which will replicate multiple times and fill the gaps created by affected genes.
• Gene therapies became difficult to continue after so many failures.
• New laws are passed to keep them from repeating
Canavan Disease
• Because no treatment exists, canavan disease made it a unique case study for gene therapy
• It’s a neurological disease, so brain scans make the progress much easier and safer to track
• Treatment must be constant and timely.
Genetic Testing
• 2 basic steps:
• 1) identifying the condition
• 2) taking action against the mutant genes.
Newborn Screening• Genetic counseling involves pedigrees and
helps in weighing the options of how to conceive
• Testing is not expensive because testing for certain disorders in the metabolism requires a simple blood test
Genetic Counseling
• 2 major reasons:
• 1) prenatal counseling
• 2) a disease in the family.
• It is a “shared deliberation and decision making between the counselor and the client.”
• Confidentiality and “duty to warn” relatives is debated
Great Promise
• There is more of a need now for medical genetics due to the rare orphan diseases.
• The more physicians find out about these diseases, the better chance of new treatments for them.
• Gene therapy progress has been painstakingly slow.
• The delivered genes do not always go where intended.
• New gene defects.
• Ways to correct many of the disease Revealed a complexity to genome structure.
Minor setbacks...
In conclusion...
• Although there are draw backs, gene therapy is working.
• Patients with muscular dystrophy, cystic fibrosis, and SCID have cells that accepted and expressed therapeutic genes.
• The challenge is find the right vector to deliver a sustained, targeted, and safe genetic correction.
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[15] Limb Girdle Muscular Dystrophy Type 1A. (2006, December ). Retrieved March 2, 2008, from stompy2.tripod.com/md.html