DNA technology in diseases and medicine | Anthropology Optional for UPSC PDF Download

DNA Technology and Its use in Disease and Medicine

Recombinant DNA (rDNA) technology, also known as genetic engineering, involves artificial modification of the genetic constitution of a living cell by introduction of foreign DNA through experimental technique. The DNA technology has made a significant contribution in the prevention, diagnosis and treatment of diseases.  
A few of the applications of recombinant DNA are discussed below:

• DNA Probes: DNA probes are short segments of DNA that distinguish corresponding sequences in DNA and hence permit recognition of specific DNA sequences. This technique is mainly helpful in diagnosis. DNA probes can hybridize with specific DNA sequences and permit the recognition of specific parasites. Probes resultant by recombinant DNA methods are extensively used in prenatal detection of disease: for example, in detecting genetic disorders like cystic fibrosis, Huntington disease, sickle-cell anemia etc. In a few cases, probes resultant from the gene itself is used and, in extra cases, restriction fragment length polymorphisms genetically associated to the disease gene are engaged.  If the disease gene itself, or a region close to it in the chromosome, differs from the normal chromosome in the positions of one or more cleavage sites for restriction enzymes, then these differences can be detected with southern blot i.e. with the use of cloned DNA from the region as the probe. The genotype of the fetus can, therefore, be determined since the restriction fragments present in its DNA. These techniques are very responsive and can be carried out as soon as tissue from the fetus-or still from the placenta – can be obtained. DNA probes have been developed for Leishmania, Trypnosoma, plasmodium, Schistosoma, Wuchereria and some additional human parasites.  DNA probes can also be used to recognise viruses which were previously hard to culture.
• Gene Therapy: The hereditary disease in particular can be treated with Gene therapy. Gene Therapy is the insertion of genes into an individual’s cells to treat a disease. Gene therapy normally aims to supplement a faulty mutant allele with a functional one. In the majority gene therapy studies, a normal gene is inserted into the genome to supplement an abnormal disease causing gene. A carrier, called a vector, must be used to deliver the therapeutic gene to the patient’s target cells. Presently, the most widespread vector is a virus that has been genetically changed to carry normal human DNA. The vector unloads its genetic material containing the therapeutic human gene into the target cell. The creation of an efficient protein product from the therapeutic gene restores the target cell to a normal state. 
• Production of hormones and Proteins: Using DNA technique, the genes responsible for the production of hormones and proteins can be introduced into bacteria by vectors. These genetically changed bacteria produce greater amounts of these substances. The hormones like insulin, human growth hormones, somatostatin, erythropoietin etc. are being produced using this DNA technique. The most important application of genetic engineering is the production of large quantities of particular proteins that are otherwise hard to acquire. Urokinase, are industrially produced today using this DNA technique.
• Production of vaccines: The conventional vaccines are inactivated germs or their antigens. There is always a danger of contamination to use such kind of vaccines.  However the synthetic vaccines are produced by separation of pure antigens using mono-clonal antibodies. These are specific antibodies produced by Lymphocytes when they hybridize with the concerned cell. The resulting hybridoma (of Lymphocyte and the cell) can produce antibodies constantly.  In diagnosis, therapy and also in prevention such antibodies can be used. Synthetic vaccines can also be produced by transferring genes for certain antigens into bacteria. Bacteria produce antibodies in large quantities which can be used as vaccines. The vaccine for Hepatitis virus is manufactured in this manner.
• Diagnosis of Infectious Diseases: Several diseases are diagnosed by conducting definite tests. The diseases like TB and cancer are being diagnosed using Recombinant DNA technology. The other diseases like measles, small pox and hepatitis can also be diagnosed through these tests. In the diagnosis process, certain pathogens are isolated and identified, and then diagnostic kits are produced (when the genome of the specific pathogen is known to kill it or block its pathogenic activity).

This DNA technique is also used in the diagnosis of AIDS diagnosis, prenatal diagnosis, understanding the molecular basis of diseases like sickle cell anaemia, thalassemia, familial hypercholesterolemia and cystic fibrosis.