In Terry Gilliam's 1985 film "Brazil," a tiny printing error in a bureaucratic document leads to the mistaken arrest and detention of an innocent man. A single letter is changed in a file and the set of instructions are automatically followed by the authorities.

In some ways, this is analogous to the way the machinery of our cells reads the instructions contained in our DNA. Here, too, a single change can have unexpectedly far-reaching consequences but unlike the Orwellian machinery depicted in "Brazil," changes to the DNA code are not always for the worse.

A good example of this was in a paper published this week in the journal Current Biology. It concerns a gene called MMP3, which makes a protein that affects the elasticity and thickness of blood vessels. More specifically, the researchers were looking at a length of DNA that determines how much of the blood-vessel protein is produced.