<p>Allergies are hypersensitivity reactions of the immune system to specific substances called allergens (such as pollen, stings, drugs, or food) that, in most people, result in no symptoms. A nomenclature system has been established for antigens (allergens) that cause IgE-mediated atopic allergies in humans [WHO/IUIS Allergen Nomenclature Subcommittee King T.P., Hoffmann D., Loewenstein H., Marsh D.G., Platts-Mills T.A.E., Thomas W. Bull. World Health Organ. 72:797-806(1994)]. This nomenclature system is defined by a designation that is composed of the first three letters of the genus; a space; the first letter of the species name; a space and an arabic number. In the event that two species names have identical designations, they are discriminated from one another by adding one or more letters (as necessary) to each species designation.</p><p> The allergens in this family include allergens with the following designations: Aln g 1, Api g 1, Bet v 1, Car b 1, Cor a 1, Dau c 1, Mal d 1 and Pru a 1.</p> <p> Trees within the order Fagales possess particularly potent allergens, e.g. Bet v1, the major White Birch (<taxon tax_id="3505">Betula verrucosa</taxon>) pollen antigen. Bet v1 is the main cause of type I allergies observed in early spring. Type I, or immunoglobulin E-mediated (IgE-mediated) allergies affect 1 in 5 people in Europe and North America. Commonly-observed symptoms are hay fever, dermatitis, asthma and, in severe cases, anaphylactic shock. First contact with these allergens results in sensitisation; subsequent contact produces a cross-linking reaction of IgE on mast cells and concomitant release of histamine. The inevitable symptoms of an allergic reaction ensue.</p><p>Recent NMR analysis [<cite idref="PUB00002961"/>] has confirmed earlier predictions of the protein structure and site of the major T-cell epitope [<cite idref="PUB00000255"/>]. The Bet v1 protein comprises 6 anti-parallel beta-strands and 3 alpha-helices. Four of the strands dominate the global fold, and 2 of the helices form a C-terminal amphipathic helical motif. This motif is believed to be the T-cell epitope. Other proteins belonging to this family include the major pollen allergens:<ul><li>Aln g I from <taxon tax_id="3517">Alnus glutinosa</taxon> (Alder);</li><li>Api G I from <taxon tax_id="4045">Apium graveolens</taxon> (Celery);</li><li>Car b I from <taxon tax_id="12990">Carpinus betulus</taxon> (European hornbeam);</li><li>Cor a I from <taxon tax_id="13451">Corylus avellana</taxon> (European hazel);</li><li>Mal d I from <taxon tax_id="3750">Malus domestica</taxon> (Apple).</li></ul> The motif is also found in:<ul><li> the wound-induced protein AoPR1 from <taxon tax_id="4686">Asparagus officinalis</taxon> (Garden asparagus);</li><li>pathogenesis-related proteins from <taxon tax_id="3885">Phaseolus vulgaris</taxon> (Kidney bean) and <taxon tax_id="4043">Petroselinum crispum</taxon> (Parsley) (PR1-1 and PR1-3);</li><li>the disease resistance response proteins, STH-2 and STH-21, from <taxon tax_id="4113">Solanum tuberosum</taxon> (Potato) and pI49, pI176 and DRRG49-C from <taxon tax_id="3888">Pisum sativum</taxon> (Garden pea); </li><li>the P. sativum abscisic acid-responsive proteins ABR17 and ABR18;</li><li> and the stress-induced protein SAM22 from <taxon tax_id="3847">Glycine max</taxon> (Soybean).</li></ul> </p>