In genetic modification (GM), a gene is transferred from one organism to another, where it continues to work. This can be useful in biotechnology because a gene that codes for a useful protein can be inserted into a bacterium or yeast cell - which then multiplies many times and produces a lot of the desired protein. This protein is sometimes a medicine, for example, insulin.
Type 1 diabetes is a disorder in which the body doesn't produce enough of the hormone insulin. This means the blood glucose levels cannot be controlled effectively. It can be treated by injecting insulin. The extra insulin allows the glucose to be taken up by the liver and other tissues, so cells get the glucose they need and blood glucose levels stay normal.
Natural insulin can be taken from the pancreases of pigs or cattle. However, this insulin causes adverse reactions in some people and its supply is limited.
Nowadays, most insulin is made using genetically modified bacteria that have had the human gene for insulin inserted into them.
This GM insulin has some advantages over insulin taken from pigs or cattle:
Gene therapy involves inserting copies of a normal allele into the chromosomes of an individual who carries a faulty allele. It is not always successful, and research is continuing.
Gene therapy involves these basic steps:
The main difficulty is usually the last step. Here are some of the problems:
It is illegal to genetically modify sex cells, such as sperm, because any changes would be inherited by the individual's offspring. Gene therapy is still not always successful and if the process caused a mutation in the DNA of the sex cell then this would be present in all of the cells of the offspring.
Instead, gene therapy is used on body cells. It means the individual could pass on their faulty allele to their children, even if they get better themselves.
Some people might not agree with changing a person's DNA.