Allopurinol-induced Severe Cutaneous Adverse Reactions Research Articles

Implementing HLA-B*58:01 testing prior to allopurinol initiation in Malaysian primary care setting: A qualitative study from doctors' and patients' perspective.

Allopurinol, the first-line treatment for chronic gout, is a common causative drug for severe cutaneous adverse reactions (SCAR). HLA-B*58:01 allele was strongly associated with allopurinol-induced SCAR in Asian countries such as Taiwan, Japan, Thailand and Malaysia. HLA-B*58:01 screening before allopurinol initiation is conditionally recommended in the Southeast-Asian population, but the uptake of this screening is slow in primary care settings, including Malaysia. This study aimed to explore the views and experiences of primary care doctors and patients with gout on implementing HLA-B*58:01 testing in Malaysia as part of a more extensive study exploring the feasibility of implementing it routinely. This qualitative study used in-depth interviews and focus group discussions to obtain information from patients with gout under follow-up in primary care and doctors who cared for them. Patients and doctors shared their gout management experiences and views on implementing HLA-B*58:01 screening in primary care. Data were coded and analysed using thematic analysis. 18 patients and 18 doctors from three different healthcare settings (university hospital, public health clinics, private general practitioner clinics) participated. The acceptability to HLA-B*58:01 screening was good among the doctors and patients. We discovered inadequate disclosure of severe side effects of allopurinol by doctors due to concerns about medication refusal by patients, which could potentially be improved by introducing HLA-B*58:01 testing. Barriers to implementation included out-of-pocket costs for patients, the cost-effectiveness of this implementation, lack of established alternative treatment pathway besides allopurinol, counselling burden and concern about genetic data security. Our participants preferred targeted screening for high-risk populations instead of universal screening. Implementing HLA-B*58:01 testing in primary care is potentially feasible if a cost-effective, targeted screening policy on high-risk groups can be developed. A clear treatment pathway for patients who test positive should be made available.

Genetic associations of human leukocyte antigen alleles in cutaneous delayed drug hypersensitivity reactions: An updated review

Abstract Cutaneous delayed drug hypersensitivity reactions (DHRs) are common iatrogenic events with potentially life-threatening consequences. Delayed DHRs encompass diverse phenotypes and can be classified by their distinct T-cell responses to drug antigens. Interaction between the immune receptors, human leukocyte antigen (HLA) and T-cell receptor (TCR), and the complementary antigenic peptide is required for the development of delayed DHRs. These idiosyncratic interactions can be elicited by the formation of antigenic drug-protein adducts (hapten hypothesis) or from direct interactions of drugs with the immune receptors (pharmacological interaction of drugs with immune receptors concept, altered peptide repertoire model, and altered TCR model). In addition, viral infections may play a role by providing co-stimulatory signals or enhancing TCR/HLA expression on T-cells. The associations of HLA allele polymorphisms and DHRs are phenotype and ethnicityspecific. The discovery of genetic polymorphisms associated with DHRs has provided a strategy to prevent and diagnose potentially life-threatening reactions. Recently, advances in next-generation sequencing technologies, such as the incorporation of whole-exome or whole-genome sequencing, enabled the comprehensive detection of susceptibility loci. Several HLA associations have shown clinical utility and cost-effectiveness, such as HLA-B*15:02 (carbamazepine-induced Stevens–Johnson syndrome/toxic epidermal necrolysis in Han Chinese), HLA-B*58:01 (allopurinol-induced severe cutaneous adverse reactions in Han Chinese), HLA-B*57:01 (abacavir hypersensitivity reactions in Caucasians), and HLA-B*13:01 (dapsone-induced drug reaction with eosinophilia and systemic symptoms in Han Chinese). Herein, we summarize the current knowledge of the pathogenesis, antigen presentation models, and HLA associations of cutaneous delayed DHRs.

WGCNA-Based DNA Methylation Profiling Analysis on Allopurinol-Induced Severe Cutaneous Adverse Reactions: A DNA Methylation Signature for Predisposing Drug Hypersensitivity.

Background: The role of aberrant DNA methylation in allopurinol-induced severe cutaneous adverse reactions (SCARs) is incompletely understood. To fill the gap, we analyze the DNA methylation profiling in allopurinol-induced Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) patients and identify the DNA methylation signature for predisposing allopurinol hypersensitivity. Methods: Genome-scale methylation analysis was conducted using the Illumina® HumanMethylation450 BeadChip. Weighted Gene Co-Expression Network Analysis (WGCNA) was utilized to analyze the data. Results: A total of 21,497 annotated promoter regions were analyzed. Ten modules were identified between allopurinol hypersensitivity and tolerance, with turquoise and yellow modules being the most significant correlation. ATG13, EPM2AIP1, and SRSF11 were the top three hub genes in the turquoise module. MIR412, MIR369, and MIR409 were the top three hub genes in the yellow module. Gene Ontology (GO) analysis revealed that the turquoise module was related to the metabolic process in intracellular organelles and the binding of various compounds, proteins, or nucleotides. The yellow module, however, was related to stimulus sensory perception in cytoskeletal elements and the activity of the receptor or transducer. Conclusion: DNA methylation plays a vital role in allopurinol-induced SCARs. DNA methylation profiling of SJS/TEN is significantly related to autophagy and microRNAs (miRNAs).

Allopurinol-induced severe cutaneous adverse reactions in Vietnamese: the role of HLA alleles and other risk factors.

Aim: To reveal the association of three class I HLA alleles, including HLA-A*33:03, HLA-B*58:01 and HLA-C*03:02, and allopurinol-induced severe cutaneous adverse reactions (SCARs) in Vietnamese patients. Methods: A case-control study on 100 allopurinol-induced SCARs patients, 183 tolerant controls and 810 population controls was performed. The HLA-A*33:03 and HLA-C*03:02 alleles were detected with the nested allele-specific PCR method; the HLA-B*58:01 allele was detected with the sequence-specific primer PCR method. Results: There were strong associations between HLA-B*58:01 and HLA-C*03:02 and allopurinol-induced SCARs. Specific associations were found between HLA-B*58:01 and Stevens-Johnson syndrome/toxic epidermal necrolysis and between HLA-C*03:02 and drug reaction with eosinophilia and systemic symptoms, with a gene dosage effect. The multivariate regression analysis indicated two significant independent risk factors: HLA-B*58:01/HLA-C*03:02 and estimated glomerular filtration rate <60ml/min/1.73m2. The specificity, positive predictive value and negative predictive value of HLA-B*58:01 testing were higher than the HLA-C*03:02 or the multiplex testing, especially in patients with impaired renal function. Conclusion: The results supported pre-treatment HLA-B*58:01 testing in Vietnamese patients with declined renal function to prevent SCARs.

The utility of surrogate markers in predicting HLA alleles associated with adverse drug reactions in Vietnamese.

Screening for HLA-A*31:01/HLA-B*15:02, HLA-B*57:01 and HLA-B*58:01 is recommended in selected populations for prevention of carbamazepine, abacavir, and allopurinol-induced severe cutaneous adverse reactions (SCARs). Compared to conventional methods for detection of HLA alleles, PCR using a tag single nucleotide polymorphism (SNP) can be cost-effective, particularly where the surrogate marker SNP is in absolute linkage disequilibrium with the relevant HLA allele. To determine guidelines for prevention of SCARs though predictive screening for the Australian Vietnamese population, the prevalence of four HLA alleles (HLA-A*31:01, HLA-B*15:02, HLA-B*57:01 and HLA-B*58:01) was examined. The utility of surrogate markers, rs2395029 and rs9263726, was investigated to predict for the presence of HLA-B*57:01 and HLA-B*58:01, respectively. Genotyping for specific HLA alleles was performed in 152 healthy Vietnamese living in Sydney using validated and established PCR-based methods. SNP genotyping was conducted using restriction-fragment-length-polymorphism analysis. rs2395029 and rs9263726 strongly correlated with HLA-B*57:01 (κ = 1, p < 0.001) and HLA-B*58:01 (Κ = 0.9, p < 0.001) with 100% sensitivity and 100% negative predictive value for predicting the HLA-B*57:01 and HLA-B*58:01 carriers, respectively. A high prevalence of carriers of HLA-A*31:01 (3.29%), HLA-B*15:02 (14.47%), HLA-B*57:01 (6.58%) and HLA-B*58:01 (9.21%) was revealed. Screening is recommended for these alleles in Australian Vietnamese prior to introducing relevant therapies. SNPs, rs2395029 and rs9263726, can be successfully used as surrogate markers for HLA-B*57:01 and HLA-B*58:01 in this population.

26546 Allopurinol induced Stevens–Johnson syndrome/DRESS overlap: A rare manifestation

Drug-induced severe cutaneous adverse reactions (SCARs) encompass a group of conditions often associated to various degrees of morbidity and mortality. Although clinical and histopathologic characteristics differ among SCARs, cutaneous manifestations can occasionally be nonspecific, representing a diagnostic challenge. Although infrequently reported, overlapping syndromes can be considered in cases fulfilling diagnostic criteria for at least 2 of these entities using the RegiSCAR validations scores. Only 5 cases of overlapping SCARs have been reported in the literature, It is still unclear if SJS/DRESS overlap is a distinct clinical entity, or a subtype of DRESS. We report the case of a 40-year-old Hispanic man with allopurinol-induced SCAR which fulfilled diagnostic criteria for both SJS and DRESS. To the best of our knowledge, only 1 case of allopurinol-induced SJS/DRESS overlap has been reported in the literature. This case highlights the importance of using RegiSCAR validation scores in the diagnosis of SCARs. Given the differences in prognosis, management, clinical course, associated morbidities and mortality that exist among SCARs, an accurate initial diagnosis is essential.

HLA-B*58:01 screening to prevent allopurinol-induced severe cutaneous adverse reactions in Chinese patients with chronic kidney disease.

Human leukocyte antigen (HLA)-B*58:01 allele is a significant risk factor for allopurinol-induced severe cutaneous adverse reactions (SCARs) which is potentially fatal. In some studies, chronic kidney disease (CKD) was also implicated to compound the risk of SCARs. We aim to investigate if pre-treatment HLA-B*58:01 screening can prevent allopurinol-induced SCARs in Chinese patients with CKD and its cost-effectiveness. We prospectively recruited Chinese CKD patients who required allopurinol during 2011-2015 and performed pre-treatment HLA testing (HLA screening group). Patients tested positive for HLA-B*58:01 were refrained from allopurinol while those tested negative were prescribed allopurinol. The incidence of SCARs in the HLA screening group was compared with the historical control in previous 5years and the cost-effectiveness of HLA testing was analyzed. In the historical control (2006-2010), 3605 patients on allopurinol were screened, 22 out of 1027 (2.14%) CKD Chinese patients newly started on allopurinol developed SCARs, including 6 SJS/TEN. In the HLA screening group, 28 out of 192 patients (14.6%) tested HLA-B*58:01 positive were advised to avoid allopurinol; 156 out of 164 HLA-B*58:01-negative patients received allopurinol and none developed SCARs. The incidence rate of SCARs was significantly lower in the HLA screening group compared with controls (0% vs 2.14% respectively, p = 0.037*). The targeted HLA screening approach was associated with lower healthcare costs compared with no HLA screening (US$ 92,430 vs US$ 281,226). Pre-treatment HLA-B*58:01 screening is cost-effective to target on patients with CKD in Chinese to prevent allopurinol-induced SCARs.

Allopurinol-Induced Severe Cutaneous Adverse Drug Reactions: An Analysis of Spontaneous Reports in Malaysia (2000-2018).

Allopurinol-induced severe cutaneous adverse drug reactions (SCARs) are potentially debilitating and life-threatening reactions, which can cause a financial burden to the healthcare system. We aimed to identify risk factors for allopurinol-induced SCARs and to assess their impact on fatality. Adverse drug reaction (ADR) reports with allopurinol as suspected drug were extracted from the Malaysian pharmacovigilance database from year 2000 to 2018. Multiple logistic regression analysis was used to identify significant predictors of allopurinol-induced SCARs. We further analysed the association between covariates and SCARs-related fatality in a separate model. Level of significance was set at p value < 0.05. Out of 1747 allopurinol ADR reports, 612 involved SCARs (35%). The strongest predictors significantly associated with SCARs were underlying renal disease (odds ratio [OR] 2.02; 95% confidence interval [CI] 1.36, 3.00; p = 0.001), allopurinol-prescribed dose of 300mg/day or higher (OR 1.72; 95% CI 1.38, 2.15; p < 0.001), females (OR 1.54; 95% CI 1.24, 1.93; p < 0.001), age 65years and above (OR 1.31; 95% CI 1.04, 1.64; p = 0.020), and allopurinol-prescribed indication. SCARs cases were higher in patients who received allopurinol for unspecified hyperuricaemia (OR 1.87; 95% CI 1.29, 2.70; p = 0.001) and off-label indications (OR 3.45; 95% CI 2.20, 5.42; p < 0.001) compared to registered indications. Fatality was associated with older age and a diagnosis of Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN) overlap or TEN. Malaysian pharmacovigilance data show that predictors of allopurinol-induced SCARs were elderly females, patients with underlying renal disease and high allopurinol doses. These patients need close monitoring and must be educated to stop allopurinol at the first signs of rash.

Genetic susceptibilities and prediction modeling of carbamazepine and allopurinol-induced severe cutaneous adverse reactions in Vietnamese.

Aims: To determine genetic susceptibility markers for carbamazepine (CBZ) and allopurinol-induced severe cutaneous adverse reactions (SCARs) in Vietnamese. Methods: A case-control study was performed involving 122 patients with CBZ or allopurinol-induced SCARs and 120 drug tolerant controls. Results:HLA-B*58:01 was strongly associated with allopurinol-induced SCARs and strongly correlated with SNP rs9263726. HLA-B*15:02 was associated with CBZ-induced Stevens-Johnson syndrome/toxic epidermal necrolysis but not with drug-induced hypersensitivity syndrome/drug rash with eosinophilia and systemic symptoms. No association was found between HLA-A*31:01 and CBZ-induced SCARs. HLA-B*58:01 and rs3909184 allele A with renal insufficiency were shown to increase the risk of allopurinol-induced SCARs. Conclusion:HLA-B*58:01 and HLA-B*15:02 confer susceptibility to allopurinol-induced SCARs and CBZ-induced SJS/TEN in Vietnamese. SNPrs9263726 can be used as a surrogate marker in identifying HLA-B*58:01.

Allopurinol-induced severe cutaneous adverse drug reactions: Risk minimization measures in Malaysia.

To describe risk minimization measures (RMMs) implemented in Malaysia for allopurinol-induced severe cutaneous adverse drug reactions (SCARs) and examine their impact using real-world data on allopurinol usage and adverse drug reaction (ADR) reports associated with allopurinol. Data on allopurinol ADR reports (2000-2018) were extracted from the Malaysian ADR database. We identified RMMs implemented between 2000 and 2018 from the minutes of relevant meetings and the national pharmacovigilance newsletter. We obtained allopurinol utilization data (2004-2018) from the Pharmaceutical Services Programme. To determine the impact of RMMs on ADR reporting, we considered ADR reports received within 1 year of RMM implementation. We used the Pearson χ2 test to examine the relation between the implementation of RMMs and allopurinol ADR reports. The 16 RMMs for allopurinol-related SCARs implemented in Malaysia involved nine risk communications, four prescriber or patient educational material, and three health system innovations. Allopurinol utilization decreased by 21.5% from 2004 to 2018. ADR reporting rates for all drugs (n = 144 507) and allopurinol (n = 1747) increased. ADR reports involving off-label use decreased by 6% from 2011. SCARs cases remained between 20% and 50%. RMMs implemented showed statistically significant reduction in ADR reports involving off-label use for August 2014 [χ2(1, N = 258) = 5.32, P = .021] and October 2016 [χ2(1, N = 349) = 3.85, P = .0499]. RMMs to promote the appropriate use of allopurinol and prescriber education have a positive impact. We need further measures to reduce the incidence and severity of allopurinol-induced SCARs, such as patient education and more research into pharmacogenetic screening.

Gene expression profiling in allopurinol-induced severe cutaneous adverse reactions in Vietnamese.

Aim: To examine gene expression in different clinical phenotypes of allopurinol-induced severe cutaneous adverse reactions (SCARs). Materials & methods: Gene expression profiling was performed using microarray on 11 RNA samples (four controls, threehypersensitivity syndrome/drug rash with eosinophilia and systemic symptoms, four Stevens-Johnson syndrome/toxic epidermal necrolysis) followed by quantitative real-time PCR in a total of 11 SCARs patients and 11 controls. Results: The biological pathways which were significantly enriched in differentially expressed genesin Stevens-Johnson syndrome/toxic epidermal necrolysis compared with hypersensitivity syndrome/drug rash with eosinophilia and systemic symptoms patients included; cell surface interactions at the vascular wall, immunoregulatory interactions at the immunological synapse and MyD88 signaling pathways. Overexpression of miR146a occurred in allopurinol-tolerant HLA-B*58:01 carriers. Conclusion: Biological pathways are identified which appear to beimplicated in determining clinical phenotypes in allopurinol-induced SCARs. Overexpression of miR146a is potentially important for allopurinol tolerance in HLA-B*58:01 carriers.

HLA-B*58: 01 association in allopurinol-induced severe cutaneous adverse reactions: the implication of ethnicity and clinical phenotypes in multiethnic Malaysia.

The association between human leukocyte antigen (HLA)-B*58:01 and risk of allopurinol-induced severe cutaneous adverse reactions (AIS) was observed across different populations. We explore the association between HLA-B*58:01 and AIS risk in multiethnic Malaysian population. The HLA-B*58:01 risk for different AIS clinical phenotypes and ethnicity was determined. We performed a case-control association study by genotyping the HLA-B alleles of 55 patients with AIS [11 toxic epidermal necrolysis (TEN), 21 Steven Johnson syndrome (SJS) 22 drug reaction wit eosinophilia and systemic symptoms (DRESS) and one acute generalized exanthematous pustulosis (AGEP)] and 42 allopurinol-tolerant controls (ATC). HLA-B*58:01 was positive in 89.1 and 14.3% of the AIS and ATC study groups [odds ratio (OR) = 49.0, 95% confidence interval (CI) = 14.6-164.4, P < 0.0001)], respectively. Our data showed that 93.8% of the AIS-SJS/TEN patients and 86.4% of the AIS-DRESS patients were HLA-B*58:01 positive (AIS-SJS/TEN, OR = 90, 95% CI = 16.9-470.1, P < 0.0001 and AIS-DRESS OR = 38, 95% CI = 8.5-169.2, P < 0.0001). Stratification by ethnicity and clinical phenotypes revealed a significant increased risk between HLA-B*58:01 and Chinese-AIS patients (OR = 137.5, 95% CI = 11.3-1680.2, P < 0.0001), in particular Chinese patients with AIS-SJS/TEN phenotype (100% HLA-B*58:01 positive). HLA-B*58:01 was positive in 90.9% Chinese AIS-DRESS (P < 0.0001). Highly significant associations of HLA-B*58:01 were observed in Malay AIS-SJS/TEN (OR = 78, 95% CI = 9.8-619.9, P < 0.0001) and Malay AIS-DRESS (OR = 54, 95% CI = 6.6-442.9, P < 0.0001). Although the number of Indian-AIS patients was relatively small (n = 2), both were HLA-B*58:01 positive. Our data suggest strong associations between HLA-B*58:01 and AIS in Malaysian population with Chinese and Malays ethnicity. The strong association was also observed in three different clinical phenotypes of AIS, mainly the AIS-SJS/TEN.

Development of a HLA-B*58:01 Allele Screening System for Allopurinol-Induced Severe Cutaneous Adverse Reactions Detection

The HLA-B*58:01 allele has been identified as a genetic marker in the fatal allopurinol-induced severe cutaneous adverse reactions (SCARs) such as Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). However, the screening of the HLA-B*58:01 allele prior to allopurinol prescription has not been implemented in hospitals, mostly due to the absence of an inexpensive and rapid screening method. In this work, we have developed a HLA-B*58:01 allele screening system which is able to give results in one and a half hour and is cheaper than any other screening instruments available. The system uses the High-Resolution Melt (HRM) method and generates difference melt curves proportional to a specific DNA’s sequence. A positive screening result will be shown if the HLA-B*58:01 allele is detected in unknown samples screened. Twelve HRM experiments were performed to optimize the system and six final optimized experiments are shown in this article, along with their difference melt curves. The system was successfully benchmarked against the Illumina Eco Real Time machine and results were also validated by Sanger sequencing. The system was also compared against other HLA screening methods available on the market. We propose that the implementation of this HLA-B*58:01 screening system in hospitals will help to decrease the number of SCARs cases and eventually eliminate them in the long run. Patients will thus be prescribed allopurinol only if they test negative for the HLA-B*58:01 gene and those who test positive will be given alternative drugs, ultimately saving lives, time of treatment and overall medical cost.

Unique Clinical Characteristics and Prognosis of Allopurinol-Induced Severe Cutaneous Adverse Reactions

Allopurinol is the most common cause of severe cutaneous adverse reactions (SCARs) in Korea due to the relatively high prevalence of the HLA-B*58:01 genotype (8%-13%). We aimed to reveal the clinical characteristics and risk factors for death in allopurinol-induced SCARs in Korea. We retrospectively reviewed the medical records of 106 subjects with allopurinol-induced SCARs and 639 subjects with other drug-induced SCARs who were enrolled in the Korean SCARs Registry (collected from 34 nationwide medical institutions) from January 2010 to December2015. Subjects with allopurinol-induced Stevens-Johnson syndrome (SJS)/toxic epidermal necrolysis (TEN) were older and had more comorbidities, longer latent periods, longer disease durations, more deranged laboratory findings, and increased disease severity resulting in a higher mortality rate (17.6% vs 7.6%; P= .020) compared with the subjects with other drug-induced SCARs. There was no significant difference in age or mortality in drug reaction with eosinophilia and systemic symptoms (DRESS). Subjects with allopurinol-induced SJS/TEN were older and had shorter latent periods and a higher mortality rate (17.6% vs 3.7%; P= .044) than those with allopurinol-induced DRESS. In allopurinol-induced SJS/TEN, significant risk factors for death included chronic renal insufficiency, intensive care unit (ICU) admission, increased blood urea nitrogen levels on admission day, serum peak eosinophil counts, baseline and peak creatinine levels, baseline and peak alanine aminotransferase levels, and decreased lowest platelet counts. In allopurinol-induced DRESS, significant risk factors for death included ICU admission and increased glucose levels on admission day. Allopurinol-induced SCARs have unique characteristics and poor prognoses with important predictive factors of death.

Utility of human leukocyte antigen-B*58: 01 genotyping and patient outcomes.

Human leukocyte antigen (HLA-B*58:01) allele screening before allopurinol administration is recommended to prevent gene-mediated severe cutaneous adverse reactions (SCARs). The objective of the analysis was to examine the clinical utility and effects of HLA-B*58:01 genotyping on patient's outcomes in a practice setting. The electronic medical records covering diagnosis, laboratory results, and prescription dispensing for patients who were newly treated with allopurinol or tested for HLA-B*58:01 were obtained from a large medical organization in Taiwan between 2010 and 2014. The uptake of HLA-B*58:01 testing, incidence of allopurinol-associated SCAR, and changes in urate-lowering agent utilization were assessed. A total of 17 532 allopurinol new users were identified from 2010 to 2014, and the HLA-B*58:01 test was ordered for 2844 (21.76%) of 13 069 new users when available between 2011 and 2014 in the study. The allopurinol-related SCAR events decreased from 0.21% (22/4460) to 0 (0/2167) after the introduction of HLA-B*58:01 testing, accompanied by a gradual increase from 8% (326/4207) to 31% (674/2167) in genotype testing rate. However, the HLA-B*58:01 testing performed before allopurinol prescription was 60.34%, and ~40% of patients were tested after already taking allopurinol. A shift from allopurinol to other urate-lowering agent regimens appeared among new allopurinol users. HLA-B*58:01 test was associated with the prevention of allopurinol-induced SCAR. The clinical utility of genotype testing may not be consistent with recommendations for testing, and treatment alternatives are a competitive intervention associated with effective implications in a real-world setting.

Efficacy of the HLA-B∗58:01 Screening Test in Preventing Allopurinol-Induced Severe Cutaneous Adverse Reactions in Patients with Chronic Renal Insufficiency—A Prospective Study

Thus far, human leukocyte antigen (HLA)-B∗58:01 has been recognized as the most important risk factor for allopurinol induced severe cutaneous adverse reactions (SCARs). To determine the usefulness of prospective screening for the HLA-B∗58:01 allele to identify Korean individuals at risk for SCARs induced by allopurinol treatment. We prospectively enrolled 542 patients with chronic renal insufficiency (CRI) from 10 hospitals nationwide and performed DNA genotyping to determine whether they carried the HLA-B∗58:01 allele. Of these, 503 HLA-B∗58:01-negative patients (92.8% of total) were treated with allopurinol, and 39 HLA-B∗58:01-positive patients (7.2%) were treated with febuxostat, an alternative drug. The patients then were followed up biweekly for 90 days using a telephone survey to monitor symptoms of adverse drug reactions, including SCARs. As a control, we used the historical incidence rate of allopurinol-induced SCARs in 4002 patients with CRI from the same hospitals who were enrolled retrospectively. Nineteen patients in the prospective cohort developed mild and transient adverse reactions but none showed allopurinol-induced SCARs. By contrast, we identified 38 patients with allopurinol-induced SCARs (0.95%) in the historical control. The difference in the incidence of allopurinol-induced SCARs between the prospective cohort and historical control was statistically significant (0% vs 0.95%, respectively; P= .029). The present study demonstrated the clinical usefulness of the HLA-B∗58:01 screening test before allopurinol administration to prevent allopurinol-induced SCARs in patients with CRI.

The Presence of HLA-B75, DR13 Homozygosity, or DR14 Additionally Increases the Risk of Allopurinol-Induced Severe Cutaneous Adverse Reactions in HLA-B*58:01 Carriers

Although HLA-B*58:01 is a well-known risk factor for the development of allopurinol-induced severe cutaneous adverse reactions (SCARs), most of the HLA-B*58:01 carriers do not suffer from SCARs despite a long-term use of allopurinol. This suggests that there are other risk factors that determine the fate of HLA-B*58:01 carriers. The aim of this study was to investigate the additional genetic factors that increase the risk of allopurinol-induced SCARs in HLA-B*58:01 carriers. The incidence of allopurinol-induced SCARs was investigated according to coexisting HLA alleles in all subjects with HLA-B*58:01 who took allopurinol between 2003 and 2017. The allopurinol tolerant group was defined as a group who took allopurinol for more than 60 days without developing hypersensitivity and was compared with the allopurinol-induced SCAR group. Among the retrospective cohort consisting of 367 HLA-B*58:01 carriers treated with allopurinol, 11 (3.0%) were diagnosed with allopurinol-induced SCARs. When HLA-B75, DR13 homozygosity, or DR14 was present, the incidence of SCARs increased up to 22.2% (odds ratio [OR], 19.568; P=.015), 20.0% (OR, 38.458; P= .001), and 10.7% (OR, 19.355; P= .004), respectively. Among the 153 HLA-B*58:01 carriers with chronic renal insufficiency (CRI), the incidence of SCARs doubled to 6.5% and further increased to 40%, 30%, and 37.5% in the presence of HLA-B75, DR13 homozygosity, or DR14, respectively. Secondary screening with HLA-B75, DR13 homozygosity, and DR14 in addition to primary screening with HLA-B*58:01 would enable a more accurate prediction of SCAR occurrence, especially in patients with CRI.

HLA-B*58:01 and rs9263726 have a linkage, but not absolute linkage disequilibrium in Han Chinese population

HLA-B*58:01 has been demonstrated to be associated with allopurinol-induced severe cutaneous adverse reactions. Since HLA-B*58:01 is too complicated to be identified, it is necessary to select an appropriate surrogate biomarker. In Japan, the rs9263726 allele was considered as a surrogate biomarker for HLA-B*58:01, but this was not the case with the Australian cohort. Due to the conflict results, in this study, we aim to demonstrate whether the rs9263726 allele is a surrogate biomarker for HLA-B*58:01 in Han Chinese population. A total of 353 samples (200 cases from the south and 153 cases from the north) were selected to detect HLA-B*58:01 and rs9263726 allele. The HLA-B*58:01 was identified by sequencing-based method, and the rs9263726 allele was identified by Taqman SNP Genotyping Assays. The results showed that the two alleles had a linkage, but not absolute linkage disequilibrium in Han Chinese population.

PSORS1C1 Hypomethylation Is Associated with Allopurinol-Induced Severe Cutaneous Adverse Reactions during Disease Onset Period: A Multicenter Retrospective Case-Control Clinical Study in Han Chinese.

Background: Allopurinol-induced severe cutaneous adverse reactions (SCARs), including drug rash with eosinophilia and systemic symptoms (DRESS), Stevens-Johnson syndrome (SJS) and toxic epidermal necrosis (TEN), are life-threatening autoimmune reactions. Evidence is growing that epigenetic variation, particularly DNA methylation, is associated with autoimmune diseases. However, the potential role of aberrant DNA methylation in allopurinol-SCARs is largely unknown.Objective: To address the knowledge gap between allopurinol-SCARs and DNA methylation, we studied the DNA methylation profiles in peripheral blood cells from allopurinol-SCARs and allopurinol-tolerant subjects.Methods: A genome-scale DNA methylation profiling was conducted using the Illumina Infinium HumanMethylation450 (HM450) platform on 15 patients with allopurinol-SCARs (3 TEN, 2 SJS/TEN overlap and 10 SJS) and 20 age- and gender-matched allopurinol-tolerant controls at disease onset. Pyrosequencing was used to validate the candidate CpG (cytosine-guanine dinucleotide) sites in an independent cohort of 40 allopurinol-SCARs and 48 allopurinol-tolerants.Results: After bioinformatics analysis of methylation data obtained from HM450 BeadChip, we identified 41 differentially methylated CpG loci (P < 0.05) annotated to 26 genes showing altered DNA methylation between allopurinol-SCARs and allopurinol-tolerants. Among these genes, significant hypomethylation of PSORS1C1 (cg24926791) was further validated in a larger sample cohort, showing significant difference between DRESS and controls (P = 0.00127), ST (SJS and TEN) and controls (P = 3.75 × 10−13), and SCARs and controls (P = 5.93 × 10−15).Conclusions: Our data identified differentially methylated genes between allopurinol-SCARs and allopurinol-tolerant controls and showed that PSORS1C1 hypomethylation was associated with allopurinol-SCARs (OR = 30.22, 95%CI = 4.73–192.96) during disease onset, suggesting that aberrant DNA methylation may be a mechanism of allopurinol-SCARs.Limitations: Firstly, the data come from whole blood samples known to possess epigenetic heterogeneity, i. e., blood samples comprise a heterogeneous cell population with varying proportions of distinct cell-types with different DNA methylation patterns. Consequently, the interpretation of DNA methylation results should be performed with great caution due to the heterogeneous nature of the sample. Secondly, whether the identified disease-associated changes of epigenome precede disease onset, or result from the disease progression, needs further investigation. Comparing the methylation status before patients develop allopurinol-SCARs and after may help examine methylation levels from disease onset to disease progression.

Risk factors of allopurinol-induced severe cutaneous adverse reactions in a Thai population.

Allopurinol is one of the most common causes of severe cutaneous adverse drug reactions (SCARs) including drug reactions with eosinophilia and systemic symptoms (DRESS), Stevens-Johnson syndrome (SJS), and toxic epidermal necrolysis (TEN). This study identified the risk factors associated with the development of allopurinol-induced SCARs in a Thai population. Eighty-six allopurinol-induced SCARs (i.e. 19 DRESS and 67 SJS/TEN) and 182 allopurinol-tolerant patients were enrolled in the study. The HLA-B*58:01 allele was determined. Clinical and medicinal data were collected. Results from multivariate analysis showed that only the HLA-B*58:01 and female sex were identified as risk factors of allopurinol-induced SCARs in this Thai population. Patients who carried the HLA-B*58:01 allele were at a higher risk of allopurinol-induced DRESS [odds ratio (OR)=149.2, 95% confidence interval (CI)=24.0-∞, P<1.00×10]. Similar results were observed in allopurinol-induced SJS/TEN (OR=175.0, 95% CI=44.3-690.9, P=1.69×10). The risk of allopurinol-induced SCARs in women was higher than that in men (OR=4.6, 95% CI=1.4-15.6, P=1.44×10). The overall mortality rate of allopurinol-induced SCARs was 11.39% and a higher mortality rate was observed in elderly women. Among the risk factors identified, the HLA-B*58:01 allele had the greatest impact on the development of both phenotypes of allopurinol-induced SCARs in this studied Thai population. In case HLA-B*58:01 genotyping cannot be accessed, close monitoring of allopurinol usage, especially in elderly women with impaired renal function, is necessary to reduce the mortality rate of these life-threatening SCARs.