Background: Food allergy is a growing health problem worldwide because of its increasing prevalence, life-threatening potential, and shortage of effective preventive treatments. In an outbreak of wheat allergy in Japan, thousands of patients had allergic reactions to wheat after using soap containing hydrolyzed wheat protein (HWP). Objectives: The aim of the present study was to investigate genetic variation that can contribute to susceptibility to HWP allergy. Methods: We conducted a genome-wide association study of HWP allergy in 452 cases and 2700 control subjects using 6.6 million genotyped or imputed single nucleotide polymorphisms. Replication was assessed by genotyping single nucleotide polymorphisms in independent samples comprising 45 patients with HWP allergy and 326 control subjects. Results: Through the genome-wide association study, we identified significant associations with the class II HLA region on 6p21 (P = 2.16 × 10−24 for rs9271588 and P = 2.96 × 10−24 for HLA-DQα1 amino acid position 34) and with the RBFOX1 locus at 16p13 (rs74575857, P = 8.4 × 10−9). The associations were also confirmed in the replication data set. Both amino acid polymorphisms (HLA-DQβ1 amino acid positions 13 and 26) located in the P4 binding pockets on the HLA-DQ molecule achieved the genome-wide significance level (P < 5.0 × 10−8). Conclusions: Our data provide the first demonstration of genetic risk for HWP allergy and show that this genetic risk is mainly represented by multiple combinations of HLA variants.
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