Modern medical research is exploring the possibility of genetic…

The idea

Inherited disorders are caused by faulty alleles passed from parents to offspring. Modern medical research is investigating whether genetic modification can correct these faults. One approach is gene therapy, in which a normal allele is inserted into a patient’s cells so that the correct protein is made. For example, in cystic fibrosis a faulty allele affects chloride transport, and researchers have tested delivering a working copy of the gene to lung cells. Another approach is to modify cells before birth or in early embryos, though this raises ethical issues. The aim is to overcome the disorder by supplying a functional gene, not to change unrelated characteristics. Success depends on delivering the gene to the right cells and getting it to work there. This is research, so treatments are not yet routine for most disorders.

What earns the marks

• Inherited disorders are caused by faulty alleles that are passed from parents to offspring.
• Genetic modification could involve inserting a normal allele into a patient’s cells so the correct protein is made.
• Gene therapy is an example of medical research aiming to overcome an inherited disorder.
• A named example, such as cystic fibrosis, can be used to show how a faulty gene affects the body.
• The aim is to treat the disorder by supplying a functional gene, not to alter unrelated characteristics.
• Ethical issues and the difficulty of delivering genes to the right cells are important considerations.

Common mistakes and how to put them right

• Saying genetic modification can cure all inherited disorders now.

  Put it right: It is research, and most treatments are not yet routine.

• Confusing gene therapy with changing a person’s whole genome.

  Put it right: Gene therapy usually targets specific cells, so describe the delivery to those cells.

• Thinking the faulty allele is removed in every case.

  Put it right: Often a working copy is added, so describe insertion of a normal allele.

Exam tips

• Name a specific inherited disorder, such as cystic fibrosis, and link it to a faulty allele and its effect.
• Use the term gene therapy and explain that a normal allele is inserted into cells.
• Mention that this is research and that ethical or delivery issues remain, to show balanced understanding.