Engineering Hypoallergenic Cats

Gene editing could create hypoallergenic cats, according to a sequence analysis of the protein that triggers allergies to cats. Some 15% of people are allergic to cats, and symptoms can be severe. Martin D. Chapman and colleagues investigated CH1 and CH2, genes that code for the allergen, Fel d 1. Cats produce Fel d 1 in their sebaceous, salivary, perianal, and lachrymal glands. The function of Fel d 1 is unknown but comparisons of Fel d 1 sequences and homologs from 276 domestic or exotic cats—including cougars, cheetahs, lions, tigers, and jaguars, among others—suggests that CH1 and CH2 have been under active selection, and thus potentially confer some fitness advantage. Fel d 1 may be involved in immune regulation, skin protection, or chemical communication among cats. However, cats genetically modified to lack CH2 seem healthy and low levels of conserved sequences between species suggest that the allergen is either nonessential or that the function of Fel d 1 varies among cat species. Two of the analyzed cats—a cougar and a black-footed cat, a small wildcat from Southern Africa—had mutations that likely prevented Fel d 1 expression, further indicating that the allergen may not be essential for cats. According to the authors, using CRISPR technology to delete CH1 and CH2 could create hypoallergenic cats.