At the start of next year, the first hypoallergenic kittens (designed to minimise the possibility of an allergic response) will go home to eager owners who have been on a waiting list for more than two years.

Allerca of San Deigo, California, says these “lifestyle pets” are so bred that their glands do not produce the protein responsible for most human cat allergies. The animals cost $4,000. And owners must pass Allerca’s finicky screening tests.

“You’re not just buying a cat; it’s a medical device that replaces shots and pills,” said Megan Young, chief executive of Allerca. “At the same time, this is a living animal, so the well-being of our product is of principal concern.”

In the US and Europe, cats are the most common pet and cat allergies are one of most common human allergies. This makes many homes cauldrons of sneezing, itchy conflicts in which a fiancé is allergic to his beloved’s favourite pet, or a mother-in-law cannot come for a festive meal because of Fluffy’s presence.

With cat owners sometimes paying thousands of dollars each year for allergy shots, antihistamines and air filters, $4,000 for a sneeze-free existence may be an acceptable price tag. More research is needed, but preliminary independent studies suggest Allerca cats do not provoke allergies.

“It may save us pain from all the medical and emotional problems,” said Christopher Cullen of New York. His girlfriend’s worsening allergies resulted in their putting up for adoption their beloved cat, Cimbi.

Cullen and his girlfriend, Cheryl Burley, have fought a losing two-year battle to engineer a tolerable co-existence with Cimbi, because Cheryl, a devoted cat lover, has had cat allergies since childhood.

The couple never laid out carpets, installed HEPA filters and vacuumed incessantly. But Cheryl’s symptoms worsened in recent months and that fragile equilibrium fell apart when the couple took in a second cat, Marley. Cheryl could not work, could not breathe and had a seizure. Finally, they took Marley to an animal shelter.

“Our whole life has gone downhill. I’m back on inhalers, eyedrops and creams. This hypoallergenic cat would be a perfect solution,” said Cheryl.

Ten volunteers with severe cat allergies were exposed to a variety of cats but showed no reaction to the Allerca cats, though all had symptoms with normal animals. “This is not a definitive study, but an interesting and intriguing concept that could really help people,” said Dr Sheldon Spector, professor of clinical medicine at the University of California.

Most human cat allergies are caused by Fel d 1, a molecule that has been sequenced and its gene mapped in the last decade. At first, Allerca scientists sought a method to delete or disable the gene. But in testing to see whether the gene had been effectively silenced, they made a fortuitous discovery: a very small number of cats carry a mutant gene that produces a modified protein, far less likely to induce allergies.

Allerca then screened thousands of cats to identify a population with the modified gene and then set those cats to breeding. Because the mutant gene is dominant, the breeding cats could be mated with normal cats to produce hypoallergenic kittens. And no special licensing or government approvals were necessary.

So, for the past few months, Allerca’s small pool of hypoallergenic cats have been busy reproducing. The breeding facility, however, “is at a secret undisclosed location,” said chief executive Ms Young.

At 10 to 12 weeks, every Allerca kitten is neutered before it is delivered. The company insists this is mainly to prevent feline overpopulation. But every Allerca cat carries the dominant hypoallergenic gene and, in theory, could produce copycat hypoallergenic kittens.

The company insists on an assiduous screening of all prospective owners and their families because the cats may still not be safe for people with the most severe forms of cat allergy, such as people who have been rushed to the hospital after anaphylactic reactions.

A Food and Drug Administration allergy test kit arrives five weeks before each kitten and all family members must be tested. Another required test detects the presence of other allergens in the house through a collection system that clients must place on their vacuum.

“We don’t want you blaming our cats if the real issue is mould or ragweed,” said Ms Young.

NYTNS