D3.293 - Selective Quail Egg Allergy Without Cross-Reactivity to Hen’s Egg: Molecular Characterization of a Pediatric Case

Hen’s egg allergy is one of the most common food allergies in childhood, whereas isolated allergy to quail egg in the absence of sensitization to homologous hen’s egg proteins is exceedingly rare. We report a case of selective anaphylaxis to quail egg, with no detectable cross-reactivity to hen’s egg, supported by detailed immunochemical characterization.

A 10-year-old girl developed an anaphylactic reaction after ingesting raw quail egg, despite previously tolerating cooked egg. Skin prick tests and serum-specific IgE to hen’s egg were negative, while prick-by-prick to quail egg was clearly positive.Protein extracts from quail egg (raw and cooked; yolk and white) and hen’s egg (raw and cooked) were analyzed. Protein profiles were assessed by SDS-PAGE, and IgE-binding patterns were evaluated using Western blot. An inhibition assay was performed to assess functional cross-reactivity.

Western blot identified IgE-binding bands at approximately 40–45 kDa and 75 kDa in raw quail egg white and whole raw egg extracts, consistent with ovalbumin and ovotransferrin, respectively. A faint ~125 kDa band was detected in quail egg yolk. Allergenic reactivity was markedly stronger in raw preparations and significantly reduced after cooking.Inhibition Western blot demonstrated complete inhibition with raw quail egg extract, but no inhibition with hen’s egg extracts (raw or cooked), indicating the absence of functional cross-reactivity between both species.

This case demonstrates selective IgE-mediated allergy to quail egg, driven by proteins predominantly found in the egg white, with no clinically relevant cross-reactivity to hen’s egg. Heating reduced IgE-binding intensity, suggesting partial thermal lability of the responsible allergens, which may have dietary implications. These findings highlight the importance of including non-chicken avian species in the diagnostic evaluation of suspected egg allergy.