Gene Therapy

A brief history of gene therapy

Gene therapy is one of the greatest wonders of genetics science. Although a genetic disorder cannot be completely cured, gene therapy can modify its seriousness and the consequences of mutant genes. The first attempt on the genetic therapy was made by Martin Cline but his efforts went unsuccessful. He was conducting a series of experiments on one of his patients to treat thalassemia (a blood disorder). Later on, ( 14th of September 1990), Ashi De-Silva has successfully treated the disease named as  ADA dependent SCID(Adenosine deaminase deficiency ). But the first somatic treatment that led to a permanent genetic change was noticed in the year 1993 where the therapy was aimed at curing malignant brain tumours by using recombinant DNA.

 

Table Of Contents

1. A brief history of gene therapy

2. What is gene therapy?

3. Gene therapy by using vectors

4. Method of gene injection

5. Risks of gene therapy

 

What is gene therapy?

Traditionally, gene therapy was all about fixing the genetic problem at its source of the defect but in reality, it is beyoned that. In gene therapy, polymers are translated into proteins that interfere with target gene expression. Such interference can make genetic expressions normal from their defective status. Artificial genes are cultured outside the human body by using recombinant technology. The cultured gene is a polymer molecule that is packed safely within a "vector".  Vectors aid in transferring the recombinant molecule inside the target cells. Since 2006, there has been an array of successful therapies that has gained popularity in India. Some of the examples of genetic therapies being conducted in the past are the treatments against chronic lymphocytic leukaemia (CLL), acute lymphocytic leukaemia (ALL), multiple myeloma, haemophilia, Parkinson’s disease, retinal diseases, X-linked SCID, ADA-SCID, and adrenoleukodystrophy. Two major approaches of gene therapy are either replace the defective gene or correct the defect. Depending upon which types of cells are to be treated, there are 2 types of gene therapies, namely, Somatic gene therapy and germ-line gene therapy. Somatic therapy is the transfer of a section of recombinant DNA to any cell of the somatic part (body part other than sexual part). Germ-line gene therapy is the transfer of a section of recombinant DNA to cells that produce eggs or sperm.

 

Gene therapy by using vectors

A gene cannot be inserted directly into the defective place. A vector or mediator such as viruses are often used to transfer the recombinant DNA complex into the host. The viral vectors can be Retrovirus, Lentivirus, Herpes virus, Adenovirus plasmid, etc.  In addition to the viruses, stem cells and liposomes also found to be useful. During the process of transfer, vectors are modified in such a way that, they do not affect the host body, instead, they can just deliver the genome to the target cells. DNA of the vector cell is being used as a medium for integration of the artificially made genome which in turn delivers the DNA to host quickly.  As a general rule, whole DNA is not going to be inserted into the target cell, instead only the genome is pushed in order to prevent contamination.

 

Method of gene injection

A sample of the patient's cells can be collected exposed to the vector in a laboratory setting to identify any unavoidable reactions and compatibility. The vector is injected by the intravenous route by using a probe directly into a specific tissue or the target cell. Below is the image showing the example of Gene therapy using adenovirus.

Gene therapyGene therapy-Image-US National Library Of Medicine

 

Risks of gene therapy

A sample of the patient's cells can be collected exposed to the vector in a laboratory setting to identify any unavoidable reactions and compatibility. The vector is injected by intravenous route by means of a  probe directly into a specific tissue -the target cell. 





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