Brazil nut allergy. A case in an 11-year-old.

Within five minutes of eating a few grams of Brazil nut, an 11 1/2-year-old girl developed an oral syndrome of allergy followed by laryngeal angioedema. She had a personal history of atopic dermatitis and a family history of atopy. Both the prick test and the RAST for Brazil nut were positive (15 x 22-mm induration and 0.86 kU/L, respectively). Tests were negative for other specific serum IgEs including Dermatophagoides pteronyssinus, the Fx5 food mix, hazelnut, coconut, and pollens of dactyls and phleoles. The lip challenge test was strongly positive (grade 3), a finding which, together with ethical considerations, led to a decision not to perform an oral challenge test. Fewer than 20 similar cases have been reported. Symptoms, which consisted primarily of laryngeal angioedema, developed:very abruptly, within a few minutes of ingestion of the nuts. More than half the patients were younger than 10-12 years. The incidence of Brazil nut allergy seems to be rising in northern Europe. A number of crops (soybean, peas, rapeseed) have been enriched via transgenic technology in several proteins including protein 2S of Brazil nuts. In patients with a history of Brazil nut allergy, foods derived from these crops are as allergenic as Brazil nuts themselves. This illustrates the need for greater precautions during the various steps involved in the development of transgenic foods.