Gene therapy is the use of bioengineered cells and other biotechnology to treat human genetic disorders. It is the transfer of normal genes into body cells to correct a genetic defect.
It can be used to treat genetic diseases like Sickle Cell anaemia and severe combined immunodeficiency. SCID is caused by the defect in the genes for the enzyme adenosine deaminase. SCID patients have no functioning t-Lymphocytes and one treated with an injection of the white blood cells that have been engineered to carry the normal allele.