Biotechnological Application in Medicine

• Recombinant DNA technology has improved healthcare by enabling the mass production of safe and effective therapeutic drugs.
• Recombinant therapeutics usually do not cause unwanted immune responses like some products obtained from non-human sources.
• Around 30 recombinant therapeutics have been approved worldwide, and 12 are being marketed in India.

• Earlier, insulin was obtained from the pancreas of cattle and pigs.
• Animal insulin could cause allergy or immune reactions in some patients.
• Human insulin consists of two polypeptide chains: A chain and B chain, joined by disulfide bonds.
• Insulin is first produced as pro-insulin, which contains an extra C-peptide.
• C-peptide is removed during maturation, forming active insulin.
• In 1983, Eli Lilly produced human insulin using recombinant DNA technology.
• DNA sequences for A and B chains were inserted separately into E. coli, and the chains were later combined to form insulin.

Maturation of pro-insulin into insulin

• Gene therapy is a method used to correct a defective gene by introducing a functional copy of the gene into cells or tissues.
• The first clinical gene therapy was given in 1990 to a 4-year-old girl with ADA deficiency.
• ADA deficiency results from the deletion of the adenosine deaminase gene, which is important for immune function.
• In one method, lymphocytes are taken from the patient, a functional ADA cDNA is introduced, and the corrected cells are returned to the body.
• This is not always permanent because lymphocytes are not immortal, so repeated infusion may be needed.
• A more permanent cure may be possible if the functional gene is introduced at an early embryonic stage.

• Early diagnosis is important for proper treatment, but conventional methods often cannot detect disease at an early stage.
• PCR, ELISA, and recombinant DNA technology help in early diagnosis.
• PCR amplifies very small amounts of nucleic acid, so it can detect pathogens before symptoms appear.
• PCR is used to detect HIV in suspected AIDS patients and mutations in genes of suspected cancer patients.
• A labelled DNA or RNA probe can identify complementary nucleic acid sequences.
• ELISA is based on antigen-antibody interaction.
• Infection can be detected either by the presence of antigens or by antibodies produced against the pathogen.

• Recombinant DNA technology mass-produces safe, human-identical therapeutics, preventing the allergic reactions caused by animal extracts.
• Genetically engineered human insulin is produced by separately synthesising the A and B chains in E. coli and then joining them.
• Gene therapy treats genetic disorders, like ADA deficiency, by inserting functional genes into a patient's extracted lymphocytes.
• Because lymphocytes have a limited lifespan, gene therapy requires periodic treatments unless performed at the embryonic stage.
• Molecular diagnostics, such as PCR and ELISA, enable highly sensitive, early detection of disease before physical symptoms even appear.