Sudden infant death syndrome: a search for allergen hypersensitivity.

Background: Sudden infant death syndrome (SIDS) remains a diagnosis by exclusion which leaves few if any pathologic clues to its etiology. Previous evaluations for anaphylaxis in SIDS have been few and limited.

Objective: To analyze forensic blood specimens for evidence of anaphylaxis in 51 (43 boys and 8 girls) children dying of SIDS and 13 (9 boys and 4 girls) age-matched controls who died from defined, nonanaphylactic causes.

Methods: Specimens collected over a 5-year period were assayed for (1) total IgE (IU/mL) by immunoenzymatic assay; (2) latex, cat, dust mite (Dermatophagoides farinae and Dermatophagoides pteronyssinus), milk, soy, wheat, peanuts, egg, and tomato specific-IgE by RAST; and (3) serum tryptase levels (U/L) by radioimmunoassay.

Results: The 51 SIDS cases (median age 3 months; range 1 to 9 months) and 13 control cases (median age 4 months; range 1 to 11 months) demonstrated similar total IgE of 9.8 +/- 1.1 IU/mL (mean +/- SEM) and 10.9 +/- 2.8 IU/mL (P = .59). The frequency of detectable (> 0.5 U/L) serum tryptase levels among SIDS cases (10/51) was similar to controls (3/13, P = .72). The frequency of positive RAST tests was 39% (20/51) in SIDS and 38% (5/13) in control subjects (P = .99). Differences in frequencies of positive RAST tests in SIDS and control cases were not statistically significant for any allergen tested. The most frequently detected allergen-specific IgE, to milk, was similar in SIDS (22%) and controls (31%, P = .48).

Conclusions: Elevated tryptase levels and allergen-specific IgE (milk, soy, wheat, peanuts, egg, tomato, dust mites, cat, and latex) were demonstrated in some infant SIDS deaths but were no more common than in controls. We conclude that anaphylaxis is probably an uncommon etiology for SIDS.