gene therapy on germline cells

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fireblaze
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gene therapy on germline cells

Post by fireblaze » Mon Aug 14, 2006 2:33 pm

i think this should be carried out. like Alzheimers

what are your views on this.

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LilKim
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Post by LilKim » Mon Aug 14, 2006 7:45 pm

the most common forms of alzheimers disease are autosomal dominant. So, genetic counselors would recommend a "trial and error" method because gene therapy would not be 'worth the effort' as a germline approach (in humans.. due to ethics!).

To give you an quick explanation of what would have to happen (for alzheimers disease) i'll give you a scenario .....

Jen and Mike are a married couple who are anxious to start a family ... however they are very concerned that they may have a child born with Alzhiemers disease because both of them have at least 2 affected family members in their respective families. Mike (a pharmacist) knows that alzheimer can be inherited and seeks a genetic counselor to help them have a heathly child

Mike and Jen find and consult with Dr. T., a genetic counselor. Dr. T. suggests that they start of by learning if they are a carrier of a common alzheimers gene. To do this, blood is drawn from Jen and Micheal and sent to a lab. A week later ... terrible news!! Although Michael is not a carrier of a common gene; Jen, is a carrier of autosomal dominant mutant APP (amyloid precursor) gene. And because she has 1 copy of the gene.. there is a significant posibility that she will have Alzeimers disease ... as well as 50% of her children .

Mike and Jen are completely devastated! But decide that they still want to have a healthy family. The genetic counselor will then give them 2 options: (based on if they have the money and their position on abortion.)

(.. assuming that Mike and Jen are millionaires)

Option #1. They have the money and they are not opposed to abortion ... Mike and Jen are sent home to concieve their child naturally. A few months later Jen is pregnant!! The are referred to a ob/gyn who is qualified to withdraw chorionic villi (CVS) from the growing fetus (10 weeks of gestation) or withdraw and early amniotic fluid (13 weeks). The 15mg of chorionic villi are withdrawn and sent to a special lab. The lab will then test the villi for the APP mutation ( the same gene mutation that Jen had.). Several days later, the results are in.. and they're bad. The Fetus also has the APP mutation. Dr. T., suggests that they abort the fetus and try again.

Jen and Mike agree ... she has the abortion. Again, a few months later she is pregnant! THe rush back to the ob.gyn to have a CVS drawn and tested. This time, good results! The baby has Mom's normal copy of the APP gene ... 9 months later Jen gives birth to a normal baby girl!

Option#2
Jen and Mike are opposed to abortion! Dr. T will suggest invito fertilization done by a facility that can remove the polar body from the mature Oocyte before and after in-vitro fertilization (see: http://en.wikipedia.org/wiki/Preimplant ... _diagnosis). The doctor can then go on to use PCR based techniques to determine and ensure the genotype of the fertilized ooctye. Of course this 'study' is done on several oocytes and the lab identifies 4 Oocytes that have a normal genotype. In the meantime, Jen is preparing for the transfer of the zygotes into her uterus for implantation. The zygotes are transferred and a few weeks later she learns that she is pregnant! The ob/gyn does on ultrasounds and "hears" 1 hearbeat. And 9 months later Jen and Mike welcome their normal, healthy son into the world.

Option1- is a common way to identify and remedy both dominant and recessive diseases in an unborn fetus.

Option2- Can also be used for dominant and recessive disease. However, it is expensive tricky... and you'll have to search for clinics that actually Do this. (so patients often have to travel ... far)

most people rely on option 1.

Hope this explanation helps!
- KIM

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