Egg allergy accounts for one of the most prevalent food hypersensitivities in industrialized countries. The majority of the relevant egg allergens have been identified in the egg white: ovomucoid (Gal d 1), a Kazal-type serine protease inhibitor; ovoalbumin (Gal d 2), a serine protease inhibitor; ovotransferrin (Gal d 3); and the egg lysozyme (Gal d 4). Gal d 6 is the yolk glycoprotein YGP42, a fragment of VTG-1. The VTG-derived proteins are the major yolk components; cleavage of VTG-1 and VTG-2 in the yolk produces apolipovitellins and phosvitins, which are components of the waterinsoluble yolk granular lipoproteins. On the other hand, the C-terminal part of VTGs gives rise to yolk glycoproteins YGP40 and YGP42, which are major components of the yolk plasma.