Recombinant Gad c 1 improves diagnostic efficacy of cod allergy but not horse mackerel allergy.

Background: Parvalbumin Gad c1 is a major cod allergen used as a follow-up marker of fish-allergic children. However, the diagnostic efficacy of recombinant Gad c 1 (rGad c 1) for fish allergy diagnosis remains controversial. This study aimed to evaluate the efficacy of rGad c1 for diagnosing cod and horse mackerel allergy.

Methods: This single-centered, retrospective study obtained oral food challenges (OFCs) information performed for cod and horse mackerel. Cod-, horse mackerel-, and rGad c1-specific immunoglobulins (sIgEs) were investigated. Diagnostic performances of these parameters were compared using areas under the curve (AUC).

Results: We enrolled 45 and 38 children with suspected cod and horse mackerel allergies, respectively. The median age (interquartile range) of children with suspected cod allergy was 5.7 (0.7-11.7) years and that of children with suspected horse mackerel allergy was 6.0 (1.0-12.3) years. Fourteen and 22 children reacted to OFCs with 25 (10-40) g of cooked pacific cod and 40 (10-40) g of cooked horse mackerel, respectively. The cod sIgE and rGad c 1 sIgE AUCs for cod allergy diagnosis were 0.85 and 0.90, respectively. For horse mackerel allergy diagnosis, AUCs of horse mackerel and rGad c 1 sIgE were 0.76 and 0.72, respectively. Both AUCs for cod and mackerel allergy were significantly different.

Conclusion: rGad c 1 sIgE is more effective than cod sIgE as a diagnostic marker of cod allergy, but less effective than horse mackerel sIgE as a diagnostic marker of horse mackerel allergy. Further studies are warranted to explore the potential applications of rGad c 1 sIgE in the diagnosis of various fish allergies.