It is important to keep in mind that Siberians are not non-allergenic, but rather, hypoallergenic (hypo- meaning “less” in Latin). Thus, typical allergic reactions can be significantly reduced with respect to certain people who have cat allergies. Decreased dander qualities is one of many reasons Siberians are still commonly sought after for this very unique trait.
According to recent studies, most allergic reactions (60% - 90%) that people have to cats are caused by a small glycoprotein called "Fel d-1." This protein is produced only in cats, and is excreted via their saliva and sebaceous glands (glands in the skin). As such, when a cat grooms itself it spreads and disperses the Fel d-1 in the cat’s fur, which in turn then breaks off and becomes airborne, contaminating the air with high levels of this allergen. Individuals allergic to cats and not other animals are usually allergic only to Fel d-1.
Because Siberians produce significantly less Fel d-1 than other breeds, allergic reactions in people can be greatly reduced or eliminated. Research on this issue has provided consistent scientific findings supporting this claim. For example, in 1999, Indoor Biotechnologies conducted tests on the fur of Siberian cats versus other breeds, with respect to the levels of Fel d-1. It found that the average cat produces an estimated 63,000 micrograms of Fel d-1 per gram, while a Siberian will produce approximately 200 micrograms per gram.
Another study in 2005 by the nonprofit organization, Siberian Research, Inc., further bolsters these findings, showing a very strong correlation between the allergen level in saliva and the perceived allergic reaction in highly allergic individuals. Siberians with very low allergen levels pass this trait to the kittens in the litter (www.siberianresearch.com ).
Most recently, a 2017 study by the Department of Veterinary Science, found multiple mutations in a small sampling of the Siberian’s genes that encode for the allergen, leading researchers to suggest that these mutations play a key role in the allergenic properties of the Fel d-1 protein (www.https://www.mdpi.com/2306-7381/4/4/63/htm ). Science based studies surrounding this topic are ongoing, and while there are encouraging and consistent findings that continue to emerge from this research, it is important to understand that allergies from cats can vary based on the individual, so there is no "one size fits all."