LONDON: Unravelling the human genome has given scientists an unexpected headache: mutant mouse overload.

They have discovered their animal containment buildings and cages could soon be overrun by hundreds of thousands of new strains of genetically engineered rodents needed to make sense of data generated by the human genome project.

Tens of millions of mice could be involved in this research initiative over the next two or three decades — after years in which scientists have managed to make serious reductions in mice experiment numbers.

“It’s a nightmare,” admitted one of the world’s leading BSE researchers, Dr Adriano Aguzzi, of Zurich University. “Laboratory mice cost a great deal of money to feed, house and look after, and the problem is getting bigger every day.”

Last year, scientists on both sides of the Atlantic revealed they had sequenced all 30,000 of the genes that make up a human being.

What was overlooked was the time and effort — and numbers of mice kitted out with human genes — required to turn raw data into practical science.

Genetic arithmetic indicates that at least 30,000 strains of mice, and thus hundreds of thousands of individual mice, will be needed to unravel the behaviour of every single human gene. In fact, the figure will be closer to 150,000 strains, representing more than a million mutant mice, because individual genes usually come in different varieties or mutations.

Each mouse in a laboratory costs about $3 a week to feed and keep warm. “For our laboratory, which has a relatively small number of mice, that represents an annual bill of more than $350,000,” said Aguzzi.

—Dawn/The Observer News Service.