Genetic Technology Applied to Medicine

2026 Syllabus Objectives

By the end of these notes, you should be able to:

  1. Explain the advantages of using recombinant human proteins to treat disease, using the examples insulin, factor VIII and adenosine deaminase
  2. Outline the advantages of genetic screening, using the examples of breast cancer (BRCA1 and BRCA2), Huntington's disease and cystic fibrosis
  3. Outline how genetic diseases can be treated with gene therapy, using the examples severe combined immunodeficiency (SCID) and inherited eye diseases
  4. Discuss the social and ethical considerations of using genetic screening and gene therapy in medicine

1. Recombinant Human Proteins in Medicine

https://cambridgeassistant.com

What are Recombinant Human Proteins?

Recombinant human proteins are proteins made using genetic engineering. Scientists take the human gene that codes for a specific protein and insert it into bacteria or yeast cells. These microorganisms then produce the human protein, which can be collected and purified for medical use.

This is different from the old method of extracting proteins from animals or human donors, which had many problems.

Example 1: Insulin

What is insulin? Insulin is a hormone that controls blood sugar (glucose) levels. People with diabetes cannot produce enough insulin, so they need regular insulin injections.

Advantages of genetically engineered human insulin:

Medical benefits:

  • Less likely to cause allergic reactions — In the past, insulin was extracted from pigs or cows. Some patients developed allergic reactions to this animal insulin because their immune system recognized it as foreign. Human insulin made by bacteria is identical to the insulin in our bodies, so allergic reactions are rare.

  • More effective at reducing blood glucose — Genetically engineered human insulin binds better to insulin receptors on our cells. The insulin receptor is like a lock on the outside of cells, and insulin is the key. When insulin binds to the receptor, it allows glucose to enter the cell. Because human insulin fits the receptor perfectly, it works more efficiently than animal insulin.

  • Faster onset of action — Genetically engineered human insulin starts working more quickly after injection, helping to control blood sugar levels faster.

  • Less likely to cause tolerance — Tolerance means that over time, a patient might need higher doses of a drug to get the same effect. Human insulin is less likely to cause this problem compared to animal insulin.

Economic benefits:

  • Cheaper to produce on a large scale — Once the production system is set up, bacteria can make large amounts of insulin relatively cheaply. This makes insulin more affordable and accessible to patients worldwide.

Ethical and religious benefits:

  • Acceptable to all religious groups — Some religions forbid the use of products from pigs or cows. Genetically engineered human insulin is made by bacteria, so it is acceptable to people of all faiths.

Example 2: Factor VIII

What is Factor VIII? Factor VIII is a protein needed for blood clotting. People with haemophilia A lack Factor VIII, so their blood cannot clot properly. Even small cuts can cause serious bleeding.

Advantages of recombinant human Factor VIII:

  • Safer than donor blood — Previously, Factor VIII was extracted from donated human blood. This carried risks of transmitting diseases like HIV and hepatitis. Recombinant Factor VIII is made by genetically engineered cells in controlled conditions, eliminating the risk of blood-borne infections.

  • Reliable supply — The supply of Factor VIII no longer depends on blood donations, which can be unpredictable. Genetically engineered cells can produce Factor VIII continuously.

  • Identical to human Factor VIII — Like insulin, recombinant Factor VIII is exactly the same as the natural human protein, so it works effectively without causing immune reactions.

  • Pure and consistent quality — Each batch of recombinant Factor VIII has the same quality and purity, making treatment more predictable and effective.

Example 3: Adenosine Deaminase (ADA)

What is adenosine deaminase? Adenosine deaminase (ADA) is an enzyme that breaks down toxic substances in cells, especially in white blood cells (the cells that fight infections). Without ADA, these toxic substances build up and kill white blood cells.

Why is ADA needed? People with severe combined immunodeficiency (SCID) caused by ADA deficiency lack this enzyme. Their immune system cannot function, making them extremely vulnerable to infections.

Advantages of recombinant human ADA:

  • Life-saving treatment — Before recombinant ADA was available, children with ADA-SCID often died from infections in early childhood. Recombinant ADA can keep patients alive.

  • Allows immune system to function — Regular injections of recombinant ADA break down the toxic substances, allowing white blood cells to survive and the immune system to work.

  • Safer than bone marrow transplants — Bone marrow transplants can cure SCID but require a matching donor and carry risks of rejection. Recombinant ADA provides an alternative treatment option.

  • Improved quality of life — Patients receiving ADA treatment can live more normal lives, though they need regular injections.

Sign in to view full notes