Gene Therapy Introduction

Types of gene therapy

There are two forms of gene therapy – Somatic gene therapy and Germ line gene therapy.

• Somatic gene therapy involves the manipulation of gene expression in cells that will be corrective to the patient     but not inherited to the next generation. Somatic cell gene     therapy is at an early stage of development.
• Germ line gene therapy involves the genetic modification of germ cells (sperms and eggs) in order to prevent a genetic defect from being transmitted to future generations. 

Various strategies involved in somatic cell gene therapy are emerging and can be grouped under two broad categories as ex vivo and in vivo gene therapy:
  
Ex vivo gene therapy:

. Ex vivo gene therapy involves following procedure:

1. Cells are collected from the affected individual.
  
2. The genetic defect is corrected by transferring the genes into the isolated cells.
  
3. The genetically corrected cells are selected and grown.
  
4. The genetically modified cells are transferred into the patient.
  
5. The use of patients’ owns cells (autologous cells) have no adverse immunological response after transplantation.

6. Vectors derived from mouse retroviruses are mostly used.

7. Intact particles deliver the complete vector RNA to a host cell at a high frequency.

8. Retroviruses readily infect replicating cells, so activelyh growing target cells are either treated with purified packaged retroviral vector particles directly or co cultivated with packaging cell line.

. The transferred target cells are tested to ensure that:

1. The desired gene product is produced in the gene transferred humans.

2. It is ensured that the virus does not produce its pathogenic viral cellular structures and causes infection in the human host. 

3. It is ensured that the Retroviral vector DNA has not been inserted into a size that either alters the growth properties of the cells or interferes with normal cellular functions.

Related Links
	Gene Therapy Treatment
	Genetic Counseling