They then selectively bred cats to express the protein at a lower molecular weight, reducing the likelihood of an allergic reaction.
Some feline breeds exist that are considered "hypoallergenic" or low allergy cats. This is because they produce fewer allergens than others. Cats do produce pet dander, a common , but the culprit for the estimated 10 percent of the population who are allergic to cats may be a protein, Fel d 1, that is present in cat saliva.
Technically, there are no 100 percent hypoallergenic domestic cats or cats that are completely non-allergenic. All cats produce some amount of dander, so you won't find a dander or allergen-free cat. However, there are breeds that produce less of it and therefore make good cats for people with allergies. The following list of "hypoallergenic" cats is a guideline which petMD recommends for people who want to adopt a feline, yet feel options are limited due to allergies:
Devon Rex cats are supposed to be low-allergy
Low or non allergy cats | See more about Cat hair, Cats and Allergies
Research has shown that all cats produce some Fel d1, but some cats produce considerably less than others. The Siberian Cat breed is thought to produce some of the lowest levels of Fel d1. There is strong anecdotal evidence from Siberian breeders and owners to support this theory, but scientific data is currently limited. The UC Davis University of California has now begun researching the hypoallergenic nature of Siberian cats and cats can be tested for the level of Fel d1 in their saliva.The Fel d1 production is regulated by the cat's hormones. It used to be thought that females produced lower levels of Fel d1 than males however recent research has dispelled this myth and it has been showed that both male and female Siberians can produce very low levels of the allergen. The level of Fel d1 does however increase as the cat matures and hormones increase and thus spaying/neutering will reduce the allergen levels produced by the cat. The increase of Fel d1 with age may explain why some people adopt a kitten only to find that they are allergic when the kitten grows up! That said, when living with a cat the repeated exposure to cat allergens may also reduce an individual's reaction to the cat. It is thought that high levels of exposure to the allergen may induce the production of "regulatory T cells" in the body.The Siberian Research Inc has found a strong correlation between allergen levels in cat saliva and allergic reaction experienced by cat allergy sufferers. They have found that this trait for lower Fel d1 levels found in Siberian cats is genetic and is thus passed on to offspring.The Siberian cat breed is known to be hypoallergenic (lower allergen levels, allergen free). Many people who have cat allergies find they can live symptom free with Siberian cats.