Types of Gene Therapy

The two gene therapy types are germ line gene therapy and somatic gene therapy. While the germ line type is aimed at permanent manipulation of genes in the germ cells, the somatic gene therapy refers to correction of genes in the somatic or body cells.
BiologyWise Staff
The advancement of medical science has made it possible to treat some of the irreversible, life-threatening diseases, both in humans and animals. It is amazing to know that defective DNA (deoxyribonucleic acid) of a patient suffering from genetic diseases can be replaced or repaired to treat underlying medical problems. Such an approach is called gene therapy. Based on which cell is involved in the procedure, there are two different types of gene therapy.
Gene Therapy Basics
In a cell, it is the stretch of DNA or gene that directs synthesis of specific proteins for cell expression and functioning. The sequence of nucleotides in the gene determines which type of protein is to be produced in what quantity. If there is an aberration in the sequence, the consequences are synthesis of unusual proteins, or no protein production. These in turn result in genetic disorders. Examples of the same are sickle-cell anemia, hemophilia, cystic fibrosis, Alzheimer's disease and Down's syndrome amongst others.
Gene therapy is defined as the aspect of therapeutic intervention, which involves the introduction of specific genes in a patient's cell with the help of vectors (specially viruses) or repairing the faulty genes. Thus, the abnormal genes responsible for causing ailments are rectified by inserting new genes, repairing the defective genes or removing problematic genes, so as to restore normal functioning of the bodily systems. To be more precise, treatment is proceeded to the genetic level of the individual with the help of gene therapy.
Gene Therapy Types
The main objective of gene therapy is to correct genetic diseases and disorders, which are non-responsive to the regular treatment approaches. Say for instance, chemotherapy and radiation therapy are proceeded to kill cancerous cells, but not to combat the root cause (uncontrolled cell multiplication). Gene therapy for cancer treatment is directed at correcting the faulty genes (oncogenes) or blocking them to change to normal cells. Gene therapy is broadly classified into somatic and germ line gene therapy. These various types of gene therapy are explained below.
Germ Line Gene Therapy
In this gene therapy, the procedure is centered around permanent rectification of gene in the germ cells, i.e., the eggs or the sperms. Since these germ cells are passed on from the parents to their offspring, the corrected gene is inherited to the successive generations. If this gene therapy turns out to be successful, it will help in preventing transmission of genetic problems to the next generation, especially those which run in families.
Somatic Gene Therapy
Over here, the alteration of gene is conducted to the somatic or body cells (not the germ line cells). Since the targeted genes are not transmissible from one generation to another, it manipulates body cells to combat individual health condition. As expected, the gene alteration is temporary (just for the patient) and is not inherited further to the next generation. It is a conservative therapy, and side effects (if any) are restricted to the patient only.
In the two types of gene therapy, germ line type is relatively new, and more research is underway. Till date, it has been experimented in animal studies and not in humans. For both cases of gene therapy, the protocol steps remain nearly the same. The procedure encompasses any of the techniques - insertion of a normal gene, recombination for exchanging abnormal gene with a normal one, reverse mutation technique for reversion of faulty gene to normal one and altering regulatory processes of genes to control protein synthesis. Learn more on gene therapy pros and cons.
When it comes to the application of gene therapy procedure, it does hold a specific place in medical science. But, the downside story is, this gene manipulation is not free of drawbacks. Truly speaking, it is quite early to announce the promising scopes of gene therapy. Yes, both types of therapy are accompanied with some side effects, and further studies are needed to confirm satisfactory results.