Daniel Ghirardi says he is "really attached" to his live-in girlfriend, Lindsay Carter, and she's "really attached" to her longtime cats, Nova and Brody.

	Lake Fong, Post-Gazette Even though he's allergic, Dan Ghirardi of McCandless manages under the same roof as two cats. That's his daughter Daphne, 10, playing with Nova Jones. At left is Dan's girlfriend, Lindsay and that's Brody Boppers in the foreground. Click photo for larger image. Related article About British shorthair cats

Unfortunately, Ghirardi of McCandless is extremely allergic to the cats. They give him red, itchy eyes. He can't touch them. "I have constant asthma symptoms because of them."

He lives with them anyway.

"I have become fond of the cats as well and couldn't part with them or ask my girlfriend to do so either," Ghirardi said.

Ghirardi is among an estimated 27 million Americans -- 10 percent of the population -- who are allergic to cats.

More specifically, they're allergic to a protein made in the skin and salivary glands of cats. The symptoms can range from merely annoying sneezing and runny nose to sneezing and life-threatening bronchitis.

Many of these people avoid cats like the plague. Others, like Ghirardi, who love cats or want to coexist with a loved one's cat, seek medical treatment. Still others just suffer in silence, with some eventually building a tolerance to the allergen.

By 2007, there could be a fourth option, according to Simon Brodie, chairman and CEO of the Los Angeles biotech firm Allerca Inc. His company is trying to develop a genetically modified, hypoallergenic cat. The genetic changes will be made on a breed called the British shorthair.

The cats will sell for $3,500 domestically and for up to $10,000 in Japan. Plans call for Allerca to eventually produce 200,000 of the genetically engineered cats a year.

The cats will be produced through a process called gene silencing.

According to Allerca, scientists will use a virus to disrupt the mechanism by which the allergen protein Fel d 1 is created, thus "silencing" the gene.

It's initially done at the cellular level in a test tube, Brodie said. "Basically it's done in vitro. We implant the embryos into surrogate mothers and then they give birth at normal term.

"Once we have those kittens as they mature and breed, their offspring will inherit the genetic modification."

That's if all goes to plan.

Allerca has not yet actually produced a hypoallergenic cat -- in fact, work on the project doesn't begin until March.

"About a year from now we hope to show the first one," Brodie said. "We have to make sure the cats are healthy and make sure the [allergic] people are OK with the cat."

The gene's other functions

Those are big questions. Brodie is confident both will be answered affirmatively, but others have doubts.

There is the possibility that the gene being altered does more than produce the allergen and that the cats will be negatively affected in some other way by silencing the gene.

The company believes the protein may play a role as a territory marker because neutered male cats have less of it than intact males, and females have even less. The process would not totally silence the gene, Brodie said, so that if the cat needs the protein some would still be produced.

And if Allerca is wrong?

"We stop the project," Brodie said, "but bear in mind the process is not new to us. It's been used in mice and rats, by science in general."

Nevertheless, Dr. Laura Rush, a veterinarian in the biosciences department at Ohio State University College of Veterinary Medicine, warns that disappointments are a possibility.

"It's very possible there could be unexpected consequences of silencing the gene," she said.

"You can do experiments in a petri dish and get a certain result, but when you do it in a whole live being ... it's impossible to replicate that in a petri dish so you don't know what your result is going to be."

Dr. Ina Dobrinski, director of the Center for Animal Transgenesis and Germ Cell Research for the University of Pennsylvania School of Medicine, also was skeptical.

"They seem to think the cat would not be affected by not having that protein, but I don't know how they'll know until they've tried it," she said. "I'm sure they [the proteins] have some role in nature or they wouldn't express it."

But Rush, for one, hopes Allerca is successful.

"The good thing could be if they can get this kind of technique going, then maybe they can use this for other manipulations that will result in improved health," she said.

That, Brodie said, is a long-term goal of his company.

"We may be able to knock out genes that are important to cats and dogs in developing certain diseases, like feline leukemia," he said. "We're looking at genetically immunizing cats and dogs against diseases and reversing problems that hundreds of years of breeding [have created], like hip dysplasia.

Unforeseen consequences

"Man has been genetically modifying cats and dogs [through selective breeding] for hundreds of years. The big difference is it's taken a long time. Those genetic modifications are now hurting the animal, and you can't breed it out.

"We can achieve in one year what breeders needed 300 years to do."

But solving one problem may create another.

"Genetically modifying an-imals is an imperfect science and potentially dangerous for the animals involved, [but] we also are concerned with the overpopulation pet problem," said Nancy Peterson, issues specialist with the Humane Society for the United States."

The American Humane Association shared that view. "Allerca's hope to sell 200,000 hypoallergenic cats jeopardizes the chances of homeless animals finding loving homes, and, ultimately, increases their risk of euthanasia."

The opposite is true, says Brodie. "We're helping, not adding to the shelters," he said, because people with allergies will be buying Allerca's animals and keeping them rather than turning in one that makes them sneeze.

Half of the hypoallergenic pets will be delivered to new owners outside of the United States. More than 1,000 people already have sent in $250 deposits for the cats.

For now, Ghirardi tries to cope with his girlfriend's cats under the same roof.

"Basically, I take prescription antihistamine, Allegra, every day and use an inhaler when things get really bad," he said. "This is usually about three to four times daily."

They also keep their bedroom off-limits to the cats.

A range or treatments are available for cat allergies: nasal steroids, antihistamines, a newer medicine called Singulair that is taken for allergies and asthma and allergy shots.

"The only reason we give shots are for people who don't respond to medicine, and there are people who don't want to take medications and want to take shots," said Dr. Deborah Gentile, an allergist/asthma physician at Allegheny General Hospital.

Based on her experience, people like Ghirardi rarely part with their animals.

"The inside joke in our profession is 'Honey, get rid of the kids. The cat's allergic to them,' " she said.