What is gene therapy ? How does it work ?

 

Gene therapy

• Gene therapy refers to removal of defective genes and insertion of functional genes. Because defective genes are not able to produce the right protein.

• It is used to treat some diseases by modification in content or organization of genes.

• Gene therapy may be done in terms of somatic cell therapy and germ line cell therapy. Grave disease, a disorder of thyroid gland may be cured by somatic cell therapy.

• Some immuno deficiency disorders are also treated successfully by somatic cell therapy.

Read more about the Immuno deficiency disorders

• Germ line therapy is used for correcting the defect in the reproductive cell.

• With the recent development of molecular biology, It is possible to insert the functional gene into the right location in the genome.

• Some methods of inserting alien genetic material into mammalian cell are microinjection, fusion of liposomes, use of vectors etc. In gene therapy- Target cell is removed from the body. Genetic transformation is done in vitro then it is introduced into the body of the recipient.

• In another method , an alien gene is introduced into the target cell in vitro then there is reinsertion of the modified cell into the body of the patient.

• Retrovirus  is a strong tool for gene insertion. There retroviruses are modified to serve as genetic vectors for gene therapy and other purposes.

Example of gene therapy

• Gene therapy was first applied to a four year old girl . She suffered from adenosine deaminase deficiency.

• The enzyme adenosine deaminase is very essential for the functioning of the immune system.

Read more about the Our Immune system

• This disorder is caused by the deletion of gene that is responsible for coding of Generally this disorder is treated by the bone marrow transplantation and by enzyme replacement therapy.

• In gene therapy lymphocytes are taken from the blood of patients and grown in vitro.

• A functional copy of DNA of enzyme adenosine deaminase is introduced in lymphocytes of patients by using retroviral vectors. And lymphocyte with Copies of DNA of enzyme adenosine deaminase are again inserted into the body of the patient .

• The patient needs a periodic transfusion of lymphocytes with copies of DNA of enzyme adenosine deaminase.

• A low density lipoprotein receptor gene has also been interested in hepatocytes of patient. This patient was suffered hypercholesterolemia.

• This disease is appeared due to defective gene of low density lipoprotein.

• In AIDS, a suicide gene is inserted into cytotoxic T cell with the reference of gene therapy.