HLA class II DRB1, DQB1 and DPB1 genotypic associations with peanut allergy: evidence from a family-based and case-control study.

BACKGROUND

Peanut is one of the most common foods provoking allergic reactions and is the most frequent cause of fatal and near-fatal food-induced anaphylaxis. However, as yet, little is known of the genetic and immunological mechanisms which underly peanut allergy.

OBJECTIVE

Based on findings in other allergic diseases, we have investigated whether particular human leucocyte antigen (HLA) class II genetic polymorphisms contribute to the development of peanut allergy.

METHODS

All individuals from 37 families each containing one or more peanut allergic individuals, plus nine unrelated patients (161 individuals in total, defined as the study group) were typed for the HLA class II DRB1, DQB1 and DPB1 loci, by PCR-based techniques. Genotype frequencies were compared with those found in 293 unrelated controls.

RESULTS

Four class II genotypes (DRB108 (13.7% vs 4.8%; Pc = 0.026), DRB108/12 tyr 16 (22.4% vs 8.2%; Pc = 0.021), DQB104 (12.2% vs 2.7%; Pc = 0.0026) and DPB10301 (49.1 vs 22.5%; Pc = 0.00062)) were present at a significantly higher frequency in the study group compared with controls. Three of these genotypes (DRB108 (18.0%; Pc = 0.027), DRB108/12 tyr16 (24.0%; Pc = 0.029) and DQB104 (16.7%; Pc = 0.0029)) were also significantly increased in peanut allergic individuals compared with controls. In addition, two genotypes (DPB10101 and 0201) were significantly decreased in frequency in the overall study group, but not specifically in peanut allergic individuals.

CONCLUSION

While other genetic factors may be important, results from this study indicate that HLA class II genetic polymorphism may play a role in determining susceptibility to peanut allergy.