Wednesday, 19 August 2020

What is gene therapy ?

 When we introduced some concepts in biotechnology we briefly mentioned the notion of gene therapy and alluded to it's enormous potential for treating genetic disorders. This is a fascinating and promising area of study.

             Image source: Wikipedia.Org

There are number of disorders that can be traced to a single defective gene. Some mutation has a risen, which alters the products of gene expression and the resulting protein does not perform it's function as intended. Which creates problems for that cell, and by extension the organism. But what if we could fix this gene? What is a normal allele could take the place of this defective one? That would necessarily solve the problem be done for every cell that possesses the mutation. It would solve the problem for the organism definitively curing the disease that is precisely.

What gene therapy seeks to do?

Take for example a type of severe combined immunodeficiency that causes bone marrow cells to be unable to produce a vital enzyme an issue which stems from single gene. Because bone marrow cells include stem cell that give rise to all the cells in the blood and immune system. This can be a huge problem, a solution to this is as follows. we can synthesize an RNA version of the normal allele for the gene of interest and insert it into a retrovirus.

Recall from our study of viruses that a retrovirus has the ability to generate a DNA transcript of it's RNA genome, which it then inserts into a host cell for replication. We then allow this retrovirus containing our cloned gene, to infect bone marrow cells that have been removed from the patient the virus is taken into these cells and Viral DNA containing the normal version of the gene of interest is inserted into the genome. These recombinant cells are then injected back into the bone marrow of the patient, and as these continually divide over an extended period of time, as bone marrow cells do more and more cells have the capacity to produce the vital enzyme, and the disorder is alleviated.

Gene therapy can involve inserting a normal allele into a genome to compensate for the activity of a mutated gene. It can also involve introducing a completely novel gene into an organism. It can even involved inactivation or knocking out a mutated gene, so that it will not be expressed. In addition. The novel DNA is not always delivered by a virus. There are techniques that involved the introduction of foreign genes into cells by electroporation. This is where an electric field is used to increase the permeability of the cell membrane, so DNA can pass through tiny temporary holes. DNA can even be injected into cells with incredibly thin needles.

There have been some complications with gene therapy, largely due to the uncertainty associated with where the insertion of the retroviral vactor will occur on the genome. it is also difficult to control the manner in which this new gene is expressed. However there is still cause for caution optimism, as a number of very serious genetic disease have been treated with significant success, and this is an area of ongoing study.

There are those that cite ethical concerns with this kind of practice. In addition to the obvious technical challenges is it appropriate to modify the genome of a living human? Well it is worth noting that this has already been done through blood donation and organ transplantation. These both introduce living cells with foreign DNA into someone's body.

Is gene therapy really different?

Of course one could argue that it is a slippery stape. Will this technology be used to genetically engineer humans and if so, according to what guidance? This type of thought could lead to the practice of eugenics, where by efforts are made to control the genomes of a population. This has been disastrous in the past, and under the wrong political influence, could be disastrous in the future.


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