Implications of HLA-allele associations for the study of type IV drug hypersensitivity reactions

HLA-B*13 :01 Is a Predictive Marker of Dapsone-Induced Severe Cutaneous Adverse Reactions in Thai Patients

HLA-B*13:01 allele has been identified as the genetic determinant of dapsone hypersensitivity syndrome (DHS) among leprosy and non-leprosy patients in several studies. Dapsone hydroxylamine (DDS-NHOH), an active metabolite of dapsone, has been believed to be responsible for DHS. However, studies have not highlighted the importance of other genetic polymorphisms in dapsone-induced severe cutaneous adverse reactions (SCAR). We investigated the association of HLA alleles and cytochrome P450 (CYP) alleles with dapsone-induced SCAR in Thai non-leprosy patients. A prospective cohort study, 16 Thai patients of dapsone-induced SCARs (5 SJS-TEN and 11 DRESS) and 9 Taiwanese patients of dapsone-induced SCARs (2 SJS-TEN and 7 DRESS), 40 dapsone-tolerant controls, and 470 general Thai population were enrolled. HLA class I and II alleles were genotyped using polymerase chain reaction-sequence specific oligonucleotides (PCR-SSOs). CYP2C9, CYP2C19, and CYP3A4 genotypes were determined by the TaqMan real-time PCR assay. We performed computational analyses of dapsone and DDS-NHOH interacting with HLA-B*13:01 and HLA-B*13:02 alleles by the molecular docking approach. Among all the HLA alleles, only HLA-B*13:01 allele was found to be significantly associated with dapsone-induced SCARs (OR = 39.00, 95% CI = 7.67–198.21, p = 5.3447 × 10⁻⁷), SJS-TEN (OR = 36.00, 95% CI = 3.19–405.89, p = 2.1657 × 10⁻³), and DRESS (OR = 40.50, 95% CI = 6.38–257.03, p = 1.0784 × 10⁻⁵) as compared to dapsone-tolerant controls. Also, HLA-B*13:01 allele was strongly associated with dapsone-induced SCARs in Asians (OR = 36.00, 95% CI = 8.67–149.52, p = 2.8068 × 10⁻⁷) and Taiwanese (OR = 31.50, 95% CI = 4.80–206.56, p = 2.5519 × 10⁻³). Furthermore, dapsone and DDS-NHOH fit within the extra-deep sub pocket of the antigen-binding site of the HLA-B*13:01 allele and change the antigen-recognition site. However, there was no significant association between genetic polymorphism of cytochrome P450 (CYP2C9, CYP2C19, and CYP3A4) and dapsone-induced SCARs (SJS-TEN and DRESS). The results of this study support the specific genotyping of the HLA-B*13:01 allele to avoid dapsone-induced SCARs including SJS-TEN and DRESS before initiating dapsone therapy in the Asian population.

Recent developments and highlights in drug hypersensitivity

Drug hypersensitivity reactions (DHRs) are nowadays the third cause of allergy after rhinitis and asthma with a significant increase in prevalence in both adults and paediatric population with new drugs included as culprit. For this, DHRs represent not only a health problem but also a significant financial burden for affected individuals and health systems. Mislabelling DHRs is showing to be a relevant problem for both, false label of drug allergic and false label of nonallergic. All this reinforces the need to improve accurate diagnostic approaches that allow an appropriate management. Moreover, there is a need for training both, nonallergist stakeholders and patients to improve the reaction identification and therefore decrease the mislabelling. The use of allergy cards has shown to be relevant to avoid the induction of DHRs due to the prescription of wrong medication. Recent developments over the last 2 years and highlights about risk factors, diagnostic approaches, mechanisms involved as well as prevention actions, and management have been reviewed. In these papers, it has been outlined the need for correct diagnosis and de-labelling of patients previously false-reported as allergic, which will improve the management and treatment of patients with DHRs.