D1.08 - Clinical relevance of troponin C (Cra c 6) sensitization in crustacean allergy

Tropomyosin is the main allergen in shellfish allergy; however, other allergenic components may also contribute to sensitization to these foods. Troponin C was first described as an allergen in North Sea shrimp (Cra c 6, Crangon crangon), and therefore the gastrointestinal tract has been considered the main route of exposure. Nevertheless, troponin C homologues have also been identified in house dust mites (Der p 39) and cockroaches (Bla g 6). The clinical relevance of this allergen remains unclear. This study aimed to analyze the clinical characteristics of patients sensitized to troponin C.

A descriptive, observational and retrospective study of specific IgE was performed using serum samples from patients evaluated between 2020 and 2025 at the Allergy Department of Hospital Universitari i Politècnic La Fe (Valencia, Spain). Samples were analyzed using the multiplex diagnostic platform ALEX®. Positive samples for Cra c 6 and negative for other shellfish-related allergens (Der p 10, Pan b, Pen m 1, Pen m 2, Pen m 3 and Pen m 4) were selected. The ratio between specific IgE and total IgE was calculated. Clinical data were obtained from the hospital electronic medical records (ORION Clinic).

A total of 2,869 samples were analyzed, of which 36 (1.25%) showed isolated sensitization to Cra c 6. Clinical records were available for 26 patients. Most patients had allergic rhinitis (76.9%; n=20), and eight reported symptoms compatible with crustacean allergy. Clinical manifestations included cutaneous symptoms (urticaria and angioedema) in 37.5% (n=3), oral allergy syndrome in 75% (n=6), and respiratory symptoms in 75% (n=6), such chest tightness, dyspnea, cough and wheezing, occurring after ingestion or inhalation of cooking vapors. Three patients were diagnosed with anaphylaxis and showed significantly higher Cra c 6 ratio 1 values than patients without anaphylaxis (n=5): median 3.26 (IQR 2.26–30.22) vs 0.49 (IQR 0.48–1.12), respectively (Mann–Whitney U test, p=0.036).

1.- Respiratory symptoms were frequent among patients sensitized to Cra c 6, possibly due to cross-reactivity with Der p 39. 

2.- Approximately one-third of sensitized patients developed clinical reactions after crustacean ingestion, including anaphylaxis, suggesting that troponin C may represent a clinically relevant allergen in crustacean allergy. 

3.- Higher Cra c 6 ratio values were associated with anaphylaxis, supporting its potential role as a marker of increased clinical severity.