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So, gene therapy is to take out a gene, correct its mutation, and put the corrected one back into the organism, right?

Is it also possible to take out a gene from an organism and put in a totally different one?

I read about this study where a scientist found four genes seemingly responsible for creating high, medium, low pan sensitivities. Genes: COMT, DRD2, DRD1 and OPRK1.

DRD1 - more common among people with low pain perception.

COMT and OPRK genes were seen more, for those with moderate pain.

DRD2 gene variant was more common among those with a high pain perception.

So for example, can we take out a DRD2 gene from a person who has high pain sensitivity and put DRD1 in him/her so that he/she can have low pain sensitivity?

Is that technically possible?

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  • $\begingroup$ First off we don't have yet the technology to perform gene therapy in human. Will be possible in the near future and the most likely candidate is the CRISPR/Cas9 technology. For your actual question, there are a couple of approaches, for mutation correction the idea would be to directly corrected the mutation without "swapping" genes. For your question with pain, the problem is that it is very hard to predict what will happen by taking a gene "off" and putting a new one "in". $\endgroup$ – cagliari2005 Apr 10 '15 at 16:49
  • $\begingroup$ Therefore gene therapy, at least at the beginning will be used on major genetic diseases (like the Prader-Willi syndrome or Huntington's disease) rather than playing with sensitivities. $\endgroup$ – cagliari2005 Apr 10 '15 at 16:51
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    $\begingroup$ @cagliari2005 I wouldn't say we can't do gene therapy in humans yet, but it's obviously in the early stages, glybera has been approved. And CRISPR/Cas9 would only be appropriate for certain gene therapies, such as repairing point mutations. Fixing large deletions or inversions requires delivery of whole genes. $\endgroup$ – user137 Apr 10 '15 at 16:52
  • $\begingroup$ @user137 you are right. Was thinking more along the lines of the question and for actual targeted genomic modifications. Good point though. $\endgroup$ – cagliari2005 Apr 10 '15 at 16:56
  • $\begingroup$ @user137 While gene therapy to treat a fully developed human has many obstacles and technical chances, CRISPR/Cas9 can be used for targeted gene replacement through homology directed repair addgene.org/crispr/zhang/faq/#HR $\endgroup$ – AMR Sep 4 '15 at 12:52
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It's been possible for a long time now. Take a look at this article related to trials with retroviral vectors used for gene therapy trials. A single child developed leukemia, and following that trials across the world were suspended.

The article although notes that many countries decided to proceed with trials, since as they say "for the greater good". But mainstream media articles tend to glorify the actual reasons behind such decisions, because such questions are governed by much more complex ethical considerations.

But moving on this recognised the need for targeted gene therapies, so one of the most promising techniques right now is the Crispr/Cas9 technique as noted by the comments above above.

So do we have the technology? Yes we do.

Should we go forward with it?

I would say no. But, I would also say yes.

Why such a division in opinion?

There is much that we do not understand. Until a few years ago, the non-coding part of the genome was just junk. Now, it's an essential regulatory partner. Even more recently, the understanding of chromosome architecture was not understood, now we know that Chromosome architecture has a role to play in gene expression. In 2002 epigenomics was in it's infancy, we believed "central dogma" to be a dogma, non-coding RNAs were just some junk that you tended to pick up because the transcription machinery did not know what it was doing, and chromosome architecture? that hardly mattered in the grander scheme of the cell. All in all the cell was a much simpler place. Now we know more than we did yesterday and less than we will know tomorrow, so if I was a person whose entire life is a prolonged episode of suffering I would take my current options. If I was a person who could live with a mild discomfort I would work around it.

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  • $\begingroup$ +1 as I agree in general - but the specific example of the non coding genome being thought of as junk I think is wrong. We've known there was a lot of noncoding regulatory DNA since at least the late 90s. And the ENCODE project's 'it's all functional' line was just marketing. $\endgroup$ – Dermot Harnett May 1 '16 at 16:30
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When you ask:

Is it possible to take out a gene from an organism and put in a totally different one?

The answer is yes. Gene knockout technologies are available in experimental scientific fields. You can destroy your target gene by swapping the gene with a drug resistant gene.

You can swapping genes using culturing cells, however it would be almost impossible to swap genes in cells of an animal body. But there is still hope. iPS cells can be generated from human and other animals. Then the technology can be applied to culturing iPS cells. Transplantation of differentiated iPS cells may be possible to replace tissues having a problems if anatomical structures allow you to do so.

I do not know details of pain perception, but it may be not that simple. You can classified genes by sensitivities of pain, but at biochemical level, the mechanisms to gain sensitivities may be different. I might check on this, although I might not able to draw the conclusion.

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It is possible to insert a new gene in another organism.
The technique is very new. I know I have done it at school where we had a colony of bacteria, and we did some things to them that some of those bacteria would 'adopt' a gene that would make them able to live on a different pertium dish.

If you are intrested in these subjects you should try to google on "Genetically modified bacteria".

Also here is a site that shows with a few images what technigue is actualy used: Link

Edit: As for the cutting of the DNA, for some bacteria (like E-coli) there whole genetic structure is known. So there are markers available that cut the DNA of the bacteria right at a certain place.

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    $\begingroup$ This does not answer the question, as the question is about higher organisms and nötig bacteria. Modifying bacteria is not a really new technique, it is done for about 40 years. $\endgroup$ – Chris Jul 5 '15 at 15:21

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