"For the first time, people who have been unable to own a cat because of their allergies can now enjoy a pet of their own without the associated risks and costs of allergy treatments," said Allerca Lifestyle Pets CEO Megan Young.

According to the American Academy of Allergy, Asthma and Immunology, approximately 30 million Americans suffer from some form of cat allergy. Cat allergies are caused by a protein in the cat's skin flakes and saliva deposited on the fur when the animal grooms itself by licking. It can trigger an allergic reaction in minutes if breathed by an asthma sufferer. Scientists at Allerca analyzed the genes of British and American shorthair cats to identify those with proteins that did not provoke a reaction in humans.

Allerca is a biotechnology firm from San Diego and claims to have created the allergy-free cat using a technique called genetic divergence. After identifying which specific cat proteins are linked to the allergies, they used selective breeding to produce over the course of several generations a cat without the genes for those proteins. The end result is an allergy-friendly "super cat".

The company originally planned to genetically modify cats to make them less allergenic but dropped the idea because of the risk that the animals would suffer side effects.

According to Allerca, preliminary tests on human volunteers have proved encouraging. The Scripps Research Institute, a California medical research group, is now carrying out controlled trials.

They plan to market the new cat in early 2007. The cat will cost more than 10 000 euros and Young has said the company expects to be breeding 10,000 "super cats" every year by 2009. Allerca says it has "several hundred" advance orders from the US, Canada, Sweden, France and Switzerland. According to them, sensitive owners will happily pay extra for the chance to have a cat that doesn't leave them wheezing and sneezing.

The American Society for the Protection of Cruelty to Animals (ASPCA) is cautious about the engineered cat. They said that the invention might help reduce the number of abandoned cats by allergic owners. On the other hand, "it will also be important to monitor the long term health of these cats to ensure that silencing the gene does not result in unforeseen effects on them," the ASPCA said in a statement.