Gene therapy is used to deliver functional genes or therapeutic DNA into target cells and tissues of patients suffering from genetic disorders so that the defective genes in their body can be corrected, repaired or replaced with the normal genes. Though they may provide the only clue for treating some genetic diseases; gene therapy is not without some drawbacks and moral issues which have impeded their outright global applications in hospitals. At the moment, gene therapy is only an experimental discipline that is only used in clinical trials.
One of the major problems associated with the application of gene therapy for the management of genetic diseases is that gene therapy is short-lived; and the therapeutic genes or DNA inserted into the recipient hosts patient may experience difficulty integrating into the rapidly dividing cells in the host. This is why gene therapy is often administered at several times so that the repair of the defective genes could be efficient. Other problems associated with the use of gene therapy include the reversion of the viral particle used into becoming a pathogen in the recipient host and the possibility of the virus triggering an adverse immunological response in the body of the patient.
The inserted therapeutic DNA may misfire and enter a non-target cell or tissue; and the viral vector used (i.e. viruses) may affect other cells of the body apart from the target cell. Ethically, gene therapy is not accepted in some quarters and this has limited the practice to merely clinical trials and especially for diseases for which there is no known available medical cure. As earlier said, gene therapy are usually of two types i.e. somatic gene therapy (in which body cells are targeted) and germ line gene therapy (in which the germ cells are targeted).
While gene therapy involving somatic cells may not be transferrable or inherited by the next generation, gene therapy involving the egg or sperm cells (i.e. the germ cells) can be passed on to the next generation and this may occur in cases where the inserted gene misses and enter reproductive cells. Another ethical issue surrounding gene therapy application is the notion that it uses viral vectors to deliver functional genes into host cells.
The use of viruses has posed some safety concerns about gene therapy since viral particles couldbe over-expressed in vivo or cause other pathological changes in the recipient host.The development of novel systems for the efficient delivery of therapeutic genes or DNA is critical to the clinical use of gene therapy in managing genetic disorders, and further research into this important field of molecular medicine will go a long way in coming up with sustainable measures of using the technique in clinical medicine.
Alberts B, Bray D, Johnson A, Lewis J, Raff M, Roberts K and Walter P (1998). Essential Cell Biology: An Introduction to the Molecular Biology of the Cell. Third edition. Garland Publishing Inc., New York.
Dale J (2003). Molecular genetics of bacteria. Jeremy W. Dale and Simon Park (4th eds.). John Wiley & Sons Ltd, West Sussex, UK.
Edelstein, M. L., Abedi, M. R., Wixon, J., and Edelstein, R. M. (2004). Gene therapy clinical trials worldwide 1989-2004—an overview. J Gene Med, 6: 597-602.
Ferrua, F.; Brigida, I.; Aiuti, A. (2010). Update on gene therapy for adenosine deaminase-deficient severe combined immunodeficiency. Current Opinion in Allergy and Clinical Immunology. 10 (6): 551–556.
Gardlík R, Pálffy R, Hodosy J, Lukács J, Turna J, Celec P; Pálffy; Hodosy; Lukács; Turna; Celec (2005). Vectors and delivery systems in gene therapy. Med Sci Monit. 11 (4): RA110–21.
Horn PA, Morris JC, Neff T, Kiem HP; Morris; Neff; Kiem (2004). Stem cell gene transfer—efficacy and safety in large animal studies. Mol. Ther. 10 (3): 417–31.
S Li and L Huang (2000). Nonviral gene therapy: promises and challenges. Gene Therapy, 7:31-34. www.nature.com/gt
Salmons B, Günzburg WH; Günzburg (1993). Targeting of retroviral vectors for gene therapy. Hum Gene Ther. 4 (2): 129–41.
Sambrook, J., Russell, D.W. (2001). Molecular Cloning: a Laboratory Manual, 3rd edn. Cold Spring Harbor Laboratory Press, New York.
Sheridan C (2011). Gene therapy finds its niche. Nature Biotechnology. 29 (2): 121–128.
Tamarin Robert H (2002). Principles of Genetics. Seventh edition. Tata McGraw-Hill Publishing Co Ltd, Delhi.
Twyman R.M (1998). Advanced Molecular Biology: A Concise Reference. Bios Scientiﬁc Publishers. Oxford, UK.
Vannucci, L; Lai, M; Chiuppesi, F; Ceccherini-Nelli, L; Pistello, M (2013). Viral vectors: A look back and ahead on gene transfer technology. The new microbiologica. 36 (1): 1–22.