Glycoproteins with these glyco-epitopes (known as Cross-reactive Carbohydrate Determinants, CCDs) [51], can elicit the production of antibodies in humans that, being specific for the carbohydrate target but not for the carrier proteins, can easily cross-react in in vitro allergy tests with non-homologous (but CCD-carrying) glycoproteins [27,51,52]. This evidence concerns the gene ART4 and allergic disease.