Gene therapy means putting in a working gene to a person who has a damaged gene. The European Commission has approved this method for one particular treatment. The treatment by the product Glybera uses a virus to infect muscle cells with a working copy of the gene. The European Commission has given Glybera marketing authorization, which means it can be sold throughout the EU.
One in a million people have damaged copies of the lipase gene needed to break down fats. Fat builds up in their blood; this leads to pain and inflammation of the pancreas (pancreatitis). It is life-threatening. Up to now, the only way to manage the condition is to have a very low-fat diet.
When used in this way, a virus is a vector. That means it is a carrier; the gene has been inserted into the viral genome, and the virus sticks it into the human cells. The technique is called transfection. This technique is different from the gene knockout technique, which does not use a viral vector.

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