What is gene therapy?
Genes are specific areas of DNA that encode for the proteins that are the essential engines of our organism, and if all goes well of human health. The aim of gene therapy is to correct genetic errors that lead to malfunctioning or even absent proteins, which are at the root of many diseases. Gene therapy is a relatively new therapeutic approach that is currently targeted only at somatic cells, i.e. the cells that make up the body and not at egg or sperm cells that would be passed on to children.
The most common form of gene therapy involves inserting normal, healthy genes into the patient so that the healthy gene can replace or supplement the activity of a damaged gene. To ensure that the functional gene is delivered inside cells where the protein can be made, it is carried by a ‘vector’ that can enter the cell without harming it. Vector systems that are derived from viruses for use in gene delivery are generally considered the most efficient.
A common, harmless type of virus, known as an adeno-associated virus (AAV), is often used for developing gene therapy. It is a safe vector and one that most people have already been exposed to in the course of their normal lives. When used for gene therapy, the AAV vector, which contains the therapeutic gene, is engineered in such a way that it cannot replicate.
In general, gene therapy is easier to carry out when the disease is caused by mutations in only a single gene, as in hemophilia B, as one gene is easier to introduce into a cell than several genes.
Gene therapy can also be used to neutralize faulty sections of a gene (gene silencing) and to enable to switch genes “on” or “off”. Until now, gene therapy research has mainly focused on hereditary diseases and cancers. More recently, scientists have started to look into using gene therapy for other diseases, such as cardiovascular diseases, liver diseases and CNS disorders.
A gene is an important unit of hereditary information in a living organism. It provides the code for living organisms’ traits, characteristics, functioning, and physical development. Man has around 20,000 genes that are located on 46 chromosomes.
Deoxyribonucleic acid (DNA) is a nucleic acid that contains the genetic information used in the development and functioning of all known living organisms and some viruses. The main role of DNA molecules is the long-term storage of information. DNA is often compared to a set of blueprints or a recipe, or a code, since it contains the instructions needed to construct other components of cells, such as proteins. The DNA segments that carry this genetic information are called genes, but other DNA sequences have key structural purposes, or are involved in regulating the use of this genetic information.
A chromosome is a singular piece of DNA, which contains many genes, regulatory and other elements. Chromosomes also contain DNA-bound proteins, which serve to package the DNA and control its functions. Chromosomes are found inside the nucleus of cells.
Proteins are large organic compounds made of amino acids. They are involved in many processes within cells. Proteins act as building blocks, or function as enzymes and are important in “communication” among cells. Proteins are an essential part of our diet.
Gene therapy is a technique for correcting defective or missing genes that cause disease. This can be done by inserting a correctly functioning gene into the cells of the patient, so that the cells will regain their proper function.