Designer Mice Made to Order

Raising lab animals is big business, and when it comes to the price of mice you pay extra for defects: A mouse with arthritis runs close to $200; two pairs of epileptic mice can cost 10 times that. You want three blind mice? That'll run you about $250. And for your own custom mouse, with the genetic modification of your choosing, expect to pay as much as $100,000.

Always a mainstay of scientific research, mice have become a critical tool in the quest for new drugs and medical treatments because their genes are remarkably similar to a person's. With proper manipulation -- either by man or nature -- a set of mouse genes can produce an animal with just about any human ailment, or a reasonable facsimile of it. Strains of mice that succumb to Alzheimer's disease, obesity, diabetes, cancer and countless other conditions are being used to study both the illnesses themselves and potential treatments. As many as 25 million mice are now used in experiments each year.