There are 11 allergens associated with hazelnut allergy. Three are airway allergens and the other eight are all food allergens.
Cor a 8 is a lipid transfer protein (LTP). This group of proteins commonly cause allergic symptoms.
Cor a 9 is an 11S protein (also known as legumin like). Cor a 11 is a 7S protein (also known as vicilin like) and Cor a 14 is a 2S protein. These groups of proteins are involved in seed storage and are common in many nuts and seeds. This is why a person suffering from a tree nut allergy is often allergic to most nuts and seeds.
Hazelnut allergy is often linked to LTP Syndrome, where similarly shaped proteins in other plants resemble those in hazelnuts and elicit an allergic reaction.
Common foods involved in LTP allergy include kiwi, strawberries, sunflower seeds, walnut, apple, mulberry, banana, pea, apricot, cherry, plum, almond, peach pomegranate, raspberry, tomato, grape, celery, peanut, asparagus, cabbage, broccoli, chestnut, lemon, tangerine, orange, hazelnut, lettuce, lentils, lupin, green bean, pear, mustard, wheat and maize.
Other food containing 2S albumin seed storage proteins are cashews, peanuts, almonds, mustard seed, rapeseed, turnip, chickpeas, brazil nuts, pistachio, buckwheat, soya beans, sunflower seeds, walnuts, kiwi, castor beans and sesame seeds.
There is a lot of cross reactivity between 2S and 11S seed storage proteins, the only other food containing 11S proteins not mentioned above is pumpkin.
Other foods containing 7S seed storage proteins not mentioned in the list above are lupin, lentils, macadamia, peas and mung bean.