Trajectories of egg sensitization in childhood: Two birth cohorts in Asia and Europe

Hen's egg exposure through impaired skin barrier is considered a major mechanism of sensitization to eggs. However, the impact of filaggrin (FLG) gene loss-of-function mutations on the natural history of egg sensitization lacks consensus among studies.

To evaluate the association between the natural course of egg sensitization and FLG mutations.

We used Japanese and the UK birth cohorts (CHIBA and MAAS) to identify the longitudinal patterns of egg sensitization until mid-school age and examined the relationship between the identified patterns and FLG mutations. Sensitization was assessed using egg white-specific IgE levels or skin prick tests (SPTs). Egg allergy was confirmed by parental reports and sensitization. Latent class growth analysis identified longitudinal patterns.

Three similar patterns of egg sensitization (persistent, early-onset remitting, and no/low grade classes) were identified in both cohorts, with differing prevalence estimates. The proportion of children with egg allergy in the persistent class at 7 or 8 years of age was 23% (CHIBA) and 20% (MAAS). Consistently in both cohorts, FLG mutations were significantly associated only with the persistent class. Children with FLG mutations had an approximately four-fold increased risk of being in the persistent sensitization class (RRRs: 4.3, 95%C.I. (1.2-16.0), p = .03 in CHIBA; 4.3 (1.3-14.7), p = .02 in MAAS).

FLG loss-of-function mutations are associated with persistent egg sensitization in both Japanese and European ethnicities, and the mutations might be a potential biomarker for identifying the risk of persistent egg sensitization/allergy in early infancy. Future studies should incorporate oral food challenges to confirm this relationship.