Parental eczema increases the risk of double-blind, placebo-controlled reactions to milk but not to egg, peanut or hazelnut.

BACKGROUND

While genetic factors are known to be important in the development of sensitization to foods, it is not known whether they also play a role in clinical allergic reactivity to foods.

OBJECTIVE

We aimed to determine whether parental atopic diseases are associated with a higher risk of a reaction to common allergenic foods when tested in a double-blind, placebo-controlled food challenge (DBPCFC).

METHODS

Parents of children suspected of being food allergic were interviewed about their own and their child's atopic history. Specific IgE and skin prick tests to food allergens and the outcome of food challenges in the child were recorded.

RESULTS

Data from 553 double-blind food challenges performed in 396 children were analyzed. The foods tested were milk (n = 185), egg (n = 110), peanut (n = 198) and hazelnut (n = 60). Only parental eczema was significantly associated with positive outcomes for food challenges with milk after correction for age, sex, atopic comorbidity in the child and milk-specific IgE test results (odds ratio 3.1, 95% confidence interval 1.5-6.3).

CONCLUSIONS

Children with a positive DBPCFC to milk more frequently have parents with eczema than children with a negative test. This effect of parental eczema was not seen in children challenged with egg, peanut or hazelnut. Clinical reactivity to milk may be caused by genetic factors which are shared with parental eczema to a greater extent than clinical reactivity to other foods.