Clinical spectrum of α-Gal syndrome: from immediate-type to delayed immediate-type reactions to mammalian innards and meat

The term α-Gal syndrome describes a novel IgE-mediated immediate-type allergy to the disaccharide galactose-α-1,3-galactose (α-Gal). Its classification as a syndrome is proposed on the basis of its clinical relevance in three different fields of allergy: food, drugs, and tick bites. The main focus of the present article is on α-Gal as an eliciting allergen in food allergy. It was recently shown that immediate-type allergies to pork kidney and other mammalian innards belong to the spectrum of α-Gal syndrome. These allergic reactions manifest as classic immediate-type allergies with a typical latency of under 1 h. The phenomenon of a delayed-onset immediate-type allergy with a latency of 3–6 h following ingestion of mammalian meat is considered pathognomonic for α-Gal syndrome. This clinically distinct type of presentation can be explained using the concept of food-dependent exercise-induced anaphylaxis (FDEIA). However, clinical observations and challenge testing in this constellation reveal that individual sensitivity in α-Gal patients is highly variable and which broadens our basic understanding of α-Gal syndrome.