The association between the number of HLA risk alleles and drug allergy and its implications for HLA screening - a case-control study.

Patients carrying specific HLA risk alleles are at higher risk for developing drug hypersensitivity reactions, yet pre-therapeutic screening is uncommon. We examined whether patients with a history of drug allergies have more HLA risk alleles to assess whether these patients are potential candidates for pre-therapeutic HLA screening. We performed a case-control study with patients who had a self-reported history of drug allergy (N = 94) and patients without such a history (N = 185). HLA regions were sequenced by use of Alloseq Tx for HLA-A -B, -C, -DP, -DQ and -DR genotypes. A logistic regression was performed to investigate whether the number of HLA risk alleles differed between cases and controls. Sequencing data of 279 patients were available for this analysis. There was no statistically significant difference in the mean number of unique HLA risk alleles between the cases and controls (5.31 vs 5.31, p = 0.9397). Therefore, patients with a self-reported history of drug allergy do not form a suitable group for pre-therapeutic screening for HLA risk alleles to prevent future drug allergies.