HLA-A*02:01:01/-B*35:01:01/-C*04:01:01 haplotype associated with lamotrigine-induced maculopapular exanthema in Mexican Mestizo patients

HLA allelic diversity in the Waorani population of Ecuador: Its significance to their ancestry and migration

The Waorani, an isolated indigenous tribe in Ecuador, have long been characterized by limited genetic diversity, with few studies delving into their genetic background. Human Leukocyte Antigen (HLA) genes which are located in the human major histocompatibility complex (MHC) provides valuable insights into population evolution due to its highly polymorphic nature. However, little is known about the HLA diversity and ancestry of the Waorani population. In this study, we sequenced eight HLA genes using Next Generation Sequencing (NGS) from 134 Waorani individuals and obtained up to four-field HLA allele resolution. Cluster and phylogenetic analysis show that the Waorani are genetically distant from other Ecuador populations, but instead show genetic affinities with the Puyanawa and Terena tribes from Brazil, as well as the Mixe tribe from Mexico. The identification of alleles common within the Waorani population, previously linked to specific health conditions, notably paves the way for future association analyses. This extensive study, employing Next-Generation Sequencing (NGS) technology, significantly enriches the sparse and segmented understanding of HLA diversity in the South American region. Our findings enhance the global comprehension of human genetic diversity and underscore the value of studying indigenous populations. Such research is vital for deepening our insights into human migration patterns and evolutionary processes.

Update on HLA-B*15:02 allele associated with adverse drug reactions

HLA alleles, part of the major histocompatibility complex, are strongly associated with adverse drug reactions (ADRs). This review focuses on HLA-B*15:02 and explores its association with ADRs in various ethnic populations and with different drugs, aiming to provide insights into the safe clinical use of drugs and minimize the occurrence of ADRs. Furthermore, the review explores the potential mechanisms by which HLA-B*15:02 may be associated with ADRs, aiming to gain new insights into drug modification and identification of haptens. In addition, it analyzes the frequency of the HLA-B*15:02, genotyping methods, cost-effectiveness and treatment measures for adverse reactions, thereby providing a theoretical basis for formulating clinical treatment plans.

Genotyping for HLA risk alleles versus patch tests to diagnose anti-seizure medication induced cutaneous adverse drug reactions

Aim: To provide a comparison of genotyping for HLA risk alleles versus patch testing to determine which of these two tests is a better diagnostic tool for cutaneous hypersensitivity reactions caused by anti-seizure medication.

Methods: A literature study was performed in PubMed to assess the sensitivity and specificity of HLA genotyping and patch tests for identifying anti-seizure medication induced cutaneous hypersensitivity reactions.

Results: This study shows that HLA-B*15:02 genotyping shows high sensitivity for carbamazepine-induced SJS/TEN, especially in Han Chinese and Southeast Asian patients (66.7–100.0%) whereas the sensitivity of patch tests (0.0–62,5%), HLA-A*31:01 (0–50%) and HLA-B*15:11 (18.2–42.9%) are lower. On the contrary, for carbamazepine and phenytoin induced DRESS, patch tests (respectively 70.0–88.9% and 14.3–70.0%) show higher sensitivity than HLA tests (0–66.7% and 0–12.7%). Also for lamotrigine-induced DRESS patch tests perform better than HLA-B*15:02 (33.3–40.0 versus 0%). For anti-seizure medication induced MPE and for oxcarbazepine-induced SCARs more studies are needed.

Conclusion: Use of HLA-B genotyping may aid clinicians in the diagnosis of carbamazepine, phenytoin, lamotrigine and oxcarbazepine induced SJS/TEN, particularly in Han Chinese and Southeast Asian patients. On the other hand, patch tests seem to perform better in the diagnosis of carbamazepine and phenytoin induced DRESS.

HLA pharmacogenetic markers of drug hypersensitivity from the perspective of the populations of the Greater Middle East

Specific HLA associations with drug hypersensitivity may vary between geographic regions and ethnic groups. There are little to no data related to HLA-drug hypersensitivity on populations who reside in the Greater Middle East (GME), a vast region spanning from Morocco in the west to Pakistan in the east. In this review, the authors intended to summarize the significant HLA alleles associated with hypersensitive drug reactions induced by different drugs, as have been found in different populations, and to summarize the prevalence of these alleles in the specific and diverse populations of the GME. For example, HLA-B*57:01 allele prevalence, associated with abacavir-induced hypersensitivity, ranges from 1% to 3%, and HLA-DPB1*03:01 prevalence, associated with aspirin-induced asthma, ranges from 10% to 14% in the GME population. Studying pharmacogenomic associations in the ethnic groups of the GME may allow the discovery of new associations, confirm ones found with a low evidence rate and enable cost-effectiveness analysis of allele screening before drug use.

Associations of HLA genetic variants with carbamazepine‐induced cutaneous adverse drug reactions: An updated meta‐analysis

Aggregated risk of carbamazepine (CBZ)‐induced cutaneous adverse drug reactions (cADRs) with different HLA variants are unclear and limited in terms of the power of studies. This study aimed to assess the aggregated risk of CBZ‐induced cADRs associated with carrying the following HLA variants: HLA‐B*15:02, HLA‐B*15:11, HLA‐B*15:21, HLA‐B*38:02, HLA‐B*40:01, HLA‐B*46:01, HLA‐B*58:01, HLA‐A*24:02, and HLA‐A*31:01. Literature was searched in different databases following PRISMA guidelines. The outcomes were measured as odds ratio (OR) using RevMan software by a random/fixed effects model, where p < 0.05 was set as statistical significance. In total, 46 case–control studies met the inclusion criteria and were included in this analysis consisting of 1817 cases and 6614 controls. It was found that case‐patients who carried the HLA‐B*15:02 allele were associated with a significantly increased risk of CBZ‐induced Stevens−Johnson syndrome/toxic epidermal necrolysis (SJS/TEN) compared to controls (OR 26.01; 95% CI 15.88–42.60; p < 0.00001). The aggregated risk of cADRs was slightly higher in Asian compared to Caucasian patients (Asians: OR 14.84; 95% CI 8.95–24.61; p < 0.00001; Caucasians: OR 11.65; 95% CI 1.68–80.70; p = 0.01). Further, HLA‐B*15:11, HLA‐B*15:21, or HLA‐A*31:01 allele was also associated with significantly increased risk of CBZ‐induced cADRs (HLA‐B*15:11: OR 6.08; 95% CI 2.28–16.23; p = 0.0003; HLA‐B*15:21: OR 5.37; 95% CI 2.02–14.28; p = 0.0008; HLA‐A*31:01: OR 5.92; 95% CI 4.35–8.05; p < 0.00001). Other HLA variants were not found to have any significant associations with CBZ‐induced cADRs. Strong associations between the HLA‐B*15:02, HLA‐B*15:11, HLA‐B*15:21, or HLA‐A*31:01 allele with CBZ‐induced cADRs have been established in this analysis. Pharmacogenetic testing of particular HLA alleles before initiation of CBZ therapy may be beneficial to patients and may help to eradicate cADRs substantially.

Association between human leukocyte antigens and cutaneous adverse drug reactions to antiepileptics and antibiotics in the Iranian population

In this case-control study, class І and ІІ HLA alleles in Iranian patients with benign and severe cutaneous adverse drug reactions (CADRs) due to aromatic anticonvulsants and antibiotics were evaluated. Patients diagnosed with CADRs (based on clinical and laboratory findings) with a Naranjo score of ≥4 underwent blood sampling and HLA-DNA typing. The control group comprised 90 healthy Iranian adults. Alleles with a frequency of more than two were reported. Deviations from Hardy-Weinberg equilibrium were not observed. Eighty patients with CADRs including 54 females and 26 males with a mean age of 41.49±16.08 years were enrolled in this study. The culprit drugs included anticonvulsants (lamotrigine, carbamazepine, and phenytoin) and antibiotics (ciprofloxacin and co-trimoxazole). The comparison of allele frequencies in the Iranian healthy control group and the group with benign CADRs revealed that HLA-Cw*04, and HLA-A*24 were significantly associated with lamotrigine-induced maculopapular CADRs. Furthermore, HLA-B*51 showed a significant correlation with carbamazepine-induced maculopapular CADRs. Significant associations were also detected between ciprofloxacin-induced urticarial CADRs with HLA-B*40, and HLA-DRB1*14. In the severe group, HLA-B*38 and HLA-DRB1*13 were significantly associated with lamotrigine-induced Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN). Moreover, HLA-A*31 and HLA-Cw*04 were significantly correlated with carbamazepine-induced drug reactions with eosinophilia and systemic symptoms (DRESS). HLA-B*08 also showed a significant correlation with ciprofloxacin-induced acute generalized exanthematous pustulosis (AGEP). In conclusion, Lamotrigine-induced MPE was significantly correlated with HLA-Cw*04, and HLA-A*24. Similarly, lamotrigine-induced SJS/TEN was significantly associated with HLA-B*38 and HLA-DRB1*13. Additionally, HLA-A*31 was associated with DRESS caused by carbamazepine. The most frequent CADR-inducing drugs were anticonvulsants. This article is protected by copyright. All rights reserved.

Genetics and antiepileptic mood stabilizer treatment response in bipolar disorder: what do we know?

Antiepileptic mood stabilizers (AED-MS) are often used to treat bipolar disorder (BD). Similar to other mood disorder medications, AED-MS treatment response varies between patients. Identification of biomarkers associated with treatment response may ultimately help with the delivery of individualized treatment and lead to improved treatment efficacy. Here, we conducted a narrative review of the current knowledge of the pharmacogenomics of AED-MS (valproic acid, lamotrigine and carbamazepine) treatment response in BD, including genetic contributions to AED-MS pharmacokinetics. Genes involved in neurotransmitter systems and drug transport have been shown to be associated with AED-MS treatment response. As more studies are conducted, and experimental and analytical methods advance, knowledge of AED-MS pharmacogenomics is expected to grow and contribute to precision medicine in BD.

HLA Risk Alleles in Aromatic Antiepileptic Drug-Induced Maculopapular Exanthema

To characterize human leukocyte antigen (HLA) loci as risk factors in aromatic antiepileptic drug-induced maculopapular exanthema (AED-MPE). A case-control study was performed to investigate HLA loci involved in AED-MPE in a southern Han Chinese population. Between January 2007 and June 2019, 267 patients with carbamazepine (CBZ), oxcarbazepine (OXC), or lamotrigine (LTG) associated MPE and 387 matched drug-tolerant controls from six centers were enrolled. HLA-A/B/C/DRB1 genotypes were determined using sequence-based typing. Potential risk alleles were validated by meta-analysis using data from different populations and in silico analysis of protein-drug interactions. HLA-DRB1*04:06 was significantly associated with OXC-MPE (p = 0.002, p _c = 0.04). HLA-B*38:02 was associated with CBZ-MPE (p = 0.03). When pooled, HLA-A*24:02, HLA-A*30:01, and HLA-B*35:01 additionally revealed significant association with AED-MPE. Logistic regression analysis showed a multiplicative interaction between HLA-A*24:02 and HLA-B*38:02 in CBZ-MPE. Meta-analysis of data from different populations revealed that HLA-24*:02 and HLA-A*30:01 were associated with AED-MPE (p = 0.02 and p = 0.04, respectively). In silico analysis of protein-drug interaction demonstrated that HLA-A*24:02 and HLA-A*30:01 had higher affinities with the three aromatic AEDs than the risk-free HLA-A allele. HLA-DRB1*04:06 showed relatively specific high affinity with S-monohydroxy derivative of OXC. HLA-DRB1*04:06 is a specific risk allele for OXC-induced MPE in the Southern Han Chinese. HLA-A*24:02, possibly HLA-A*30:01, are common risk factors for AED-MPE. The multiplicative risk potential between HLA-A*24:02 and HLA-B*38:02 suggests that patients with two risk alleles are at greater risk than those with one risk allele. Inclusion of these HLA alleles in pre-treatment screening would help estimating the risk of AED-MPE.

Association between HLA genotype and antiseizure medications (ASMs)-induced maculopapular eruption among epilepsy patients in Xinjiang, China

PURPOSE

To determine genetic associations between antiseizure medications (ASMs)-induced maculopapular eruption (MPE) and human leukocyte antigen (HLA) variants in Xinjiang, China.

METHODS

A total of 409 patients were enrolled in this study, including 36 subjects with ASMs-induced MPE (case group) and 373 ASMs-tolerant patients (control group). We detected the whole sequence of the HLA alleles in the 409 Uighur patients using next-generation sequencing (NGS). The carried rate of HLA alleles were compared between the case group, the control group, and the general Chinese population.

RESULTS

The carried rate of HLA-A*03:01, HLA-B*07:02, HLA-C*01:02, and HLA-DRB1 *06:09 allele was significantly higher in the ASMs-MPE group when compared with both the ASMs-tolerant group (p = 0.000, odds ratio (OR) = 23.92, 95 % confidence interval (CI) = 3.96-74.84; p = 0.000, OR = 21.40, 95 % CI = 3.55-67.52; p = 0.030, OR = 4.69, 95 % CI = 0.90-61.73 and p = 0.000, OR = 18.94, 95 % CI = 3.15-60.58; respectively), and the general Chinese population (p = 0.000, OR = 21.34, 95 % CI = 3.31-38.98; p = 0.000, OR = 23.92, 95 % CI = 3.96-74.84; p = 0.019, OR = 5.53, 95 % CI = 0.14-19.86 and p = 0.000, OR = 21.67, 95 % CI = 3.68-11.73; respectively). Moreover, the carried rate of the HLA-B*4001 allele was significantly higher in the ASMs-tolerant group when compared with the ASMs-MPE group (p = 0.024, OR = 5.13, 95 % CI = 1.01-9.99).

CONCLUSIONS

In this study, we identified for the first time that the carried rate of HLA-A*03:01, HLA-B*07:02, HLA-C*01:02, and HLA-DRB1 *06:09 allele was significantly higher in the ASMs-MPE group when compared with the ASMs-tolerant group.

The Association Between HLA-A*03:01 and HLA-B*07:02 Alleles and Oxcarbazepine-induced Maculopapular Eruption in the Uighur Chinese Population

PURPOSE

To determine genetic associations between oxcarbazepine (OXC)-induced maculopapular eruption (MPE) and human leukocyte antigen (HLA) variants in the Uighur Chinese population.

METHODS

A total of 208 patients were enrolled in this study, including 20 subjects with OXC-induced MPE (case group) and 188 OXC-tolerant patients (control group). We detected the whole sequence of the HLA alleles in the 208 Uighur patients using next-generation sequencing (NGS).

RESULTS

The carried rate of HLA-A*03:01 was significantly different between the OXC-induced MPE group and the tolerant group (7/20, 35% versus 4/188, 2.13%; P = 0.000, odds ratio [OR] = 24.77, 95% confidence interval [CI] = 6.41-95.65). Additionally, the carried rate of HLA-B*07:02 was significantly different between the OXC-induced MPE group and the tolerant group (3/20, 15% versus 2/188, 0.011%; P = 0.000, odds ratio [OR] = 16.41, 95% confidence interval (CI) = 2.56-105.09).

CONCLUSIONS

HLA-A*03:01 and HLA-B*07:02 may be the risk alleles for MPE in the Uighur Chinese population.

Genetic variants associated with T cell-mediated cutaneous adverse drug reactions: A PRISMA-compliant systematic review-An EAACI position paper

Drug hypersensitivity reactions (DHRs) are associated with high global morbidity and mortality. Cutaneous T cell-mediated reactions classically occur more than 6 hours after drug administration and include life-threatening conditions such as toxic epidermal necrolysis, Stevens-Johnson syndrome, and hypersensitivity syndrome. Over the last 20 years, significant advances have been made in our understanding of the pathogenesis of DHRs with the identification of human leukocyte antigens as predisposing factors. This has led to the development of pharmacogenetic screening tests, such as HLA-B*57:01 in abacavir therapy, which has successfully reduced the incidence of abacavir hypersensitivity reactions. We have completed a PRISMA-compliant systematic review to identify genetic associations that have been reported in DHRs. In total, 105 studies (5554 cases and 123 548 controls) have been included in the review reporting genetic associations with carbamazepine (n = 31), other aromatic antiepileptic drugs (n = 24), abacavir (n = 11), nevirapine (n = 14), trimethoprim-sulfamethoxazole (n = 11), dapsone (n = 4), allopurinol (n = 10), and other drugs (n = 5). The most commonly reported genetic variants associated with DHRs are located in human leukocyte antigen genes and genes involved in drug metabolism pathways. Increasing our understanding of genetic variants that contribute to DHRs will allow us to improve diagnosis, develop new treatments, and predict and prevent DHRs in the future.

HLA-A*02:01 allele is associated with tanshinone-induced cutaneous drug reactions in Chinese population

Tanshinone, a widely used Chinese patent medicine, has been confirmed to have various kinds of pharmacological effects although frequently causing cutaneous adverse drug reactions (cADRs). We aim to identify whether human leukocyte antigen (HLA) class I alleles are associated with tanshinone-induced cADRs in Han Chinese. The association study including 18 patients with tanshinone-induced cADRs, 67 tanshinone-tolerant volunteers, and two general population databases consisted of 10,689 and 169,995 healthy subjects was performed. The frequency of tanshinone-induced cADRs patients carrying HLA-A*02:01 was significantly higher when compared with the general control groups (OR = 6.25, Pc = 7.20 × 10^-5; OR = 7.14, Pc = 8.00 × 10^-6), and with the tolerant group (OR = 5.09, Pc = 0.024). The molecular docking assay confirmed high affinity of the ingredients of tanshinone towards HLA-A*02:01 (≤-7.5 kcal/mol). The result suggested HLA-A*02:01 may work as a promisingly predictive marker for tanshinone personalized therapy in Han Chinese.

Variation in Actionable Pharmacogenetic Markers in Natives and Mestizos From Mexico

The identification and characterization of pharmacogenetic variants in Latin American populations is still an ongoing endeavor. Here, we investigated SNVs on genes listed by the Pharmacogenomics Knowledge Base in 1284 Mestizos and 94 Natives from Mexico. Five institutional cohorts with NGS data were retrieved from different research projects at INMEGEN, sequencing files were filtered for 55 pharmacogenes present in all cohorts to identify novel and known variation. Bioinformatic tools VEP, PROVEAN, and FATHMM were used to assess, in silico, the functional impact of this variation. Next, we focused on 17 genes with actionable variants that have been clinically implemented. Allele frequencies were compared with major continental groups and differences discussed in the scope of a pharmacogenomic impact. We observed a wide genetic variability for known and novel SNVs, the largest variation was on UGT1A > ACE > COMT > ABCB1 and the lowest on APOE and NAT2. Although with allele frequencies around 1%, novel variation was observed in 16 of 17 PGKB genes. In Natives we identified 59 variants and 58 in Mestizos. Several genes did not show novel variation, on CYP2B6, CYP2D6, and CYP3A4 in Natives; and APOE, UGT1A, and VKORC1 in Mestizos. Similarities in allele frequency, comparing major continental groups for VIP pharmacogenes, hint towards a comparable PGx for drugs metabolized by UGT1A1, DPYD, ABCB1, CBR3, COMT, and TPMT; in contrast to variants on CYP3A5 and CYP2B6 for which significant MAF differences were identified. Our observations offer some discernment into the extent of pharmacogenetic variation registered up-to-date in Mexicans and contribute to quantitatively dissect actionable pharmacogenetic variants in Natives and Mestizos.

ADReCS-Target: target profiles for aiding drug safety research and application

Delivering safe and effective therapeutic treatment to patients is one of the grand challenges in modern medicine. However, drug safety research has been progressing slowly in recent years, compared to other fields such as biotechnologies and precision medicine, due to the mechanistic complexity of adverse drug reactions (ADRs). To fill up this gap, we develop a new database, the Adverse Drug Reaction Classification System-Target Profile (ADReCS-Target, http://bioinf.xmu.edu.cn/ADReCS-Target), which provides comprehensive information about ADRs caused by drug interaction with protein, gene and genetic variation. In total, ADReCS-Target includes 66,573 pairwise relations, among which 1710 are protein–ADR associations, 2613 are genetic variation–ADR associations, and 63,298 are gene–ADR associations. In a case study of exploring the mechanism of rash, we find that HLAs, C1QA and APOA1 are the key gene players and thus can be potential targets (or biomarkers) in monitoring or countermining rashes. In summary, ADReCS-Target can be a useful resource for the biomedical scientific community by serving researchers in the fields of drug development, clinical pharmacology, precision medicine, and from web lab to high-throughput computational platform. Particularly, it helps to identify drug with better ADR profile and design safer drug therapy regimen.

Oxcarbazepine-Induced Cutaneous Reaction in a Female of Mexican Ancestry

Objectives: To report an oxcarbazepine (OXC)-induced cutaneous reaction in a female of Mexican ancestry. Case Summary: A 60-year-old female of Mexican ancestry presented to clinic with a diffuse morbilliform rash, with erythema and eruptions of papules/pustules concentrated on her neck and torso. The rash appeared 1 week following the initiation of OXC for trigeminal neuralgia. Initially, the correlation between the reaction and initiation of OXC was not recognized by the provider. OXC was continued for a total of 4 weeks and several medical encounters transpired in the interim. Supportive therapy, in the form of oral antihistamines and oral/topical corticosteroids, failed to resolve the rash. A clinical pharmacist prompted the discontinuation of OXC due to suspicion that it incited the adverse reaction. Oral corticosteroid therapy was initiated and tapered over 2 weeks, with rash dissipation occurring in 1 month. Discussion: The association of OXC with the cutaneous eruption was classified as "probable" based on the Naranjo Scale. While financial resources were not available to perform genetic testing, it may be possible that the genetic status of this patient lent itself to greater potential for cutaneous reactions with OXC. Further research is needed to determine whether pharmacogenetic variables affiliated with pre-Columbian lineage may predispose individuals to specific adverse drug reactions. Conclusion: As regional genotypes disperse globally, it is imperative that clinicians are cognizant of risks regarding genetically implicated adverse drug reactions. While information is limited for certain ethnicities, it is essential that providers diligently monitor all populations for reactions characteristic to specific medications.

HLA-B*13:01 as a Risk Allele for Antiepileptic Drugs-Induced Cutaneous Adverse Reactions: Higher Risk for Cross-Reactivity?

Antiepileptic drugs frequently cause cutaneous adverse reactions (cADRs). Numerous studies have reported associations between human leukocyte antigen (HLA) alleles and cADRs caused by single antiepileptic drug in Southern Han Chinese people. However, the relationship between the HLA allele and cADRs sequentially induced by two or more antiepileptic drugs (AEDs-induced cross-reactivity) is unclear. To explore the associations between HLA alleles and AEDs-induced cross-reactivity, we prospectively recruited patients with AEDs-induced cross-reactivity from 2009 to 2017 and performed high-resolution genotyping to detect the HLA-A, B, C, and DRB1 alleles in patients for comparison with normal controls. To verify the important genotype, we compared its presence in patients with cross-reactivity to enlarged normal controls, and its presence in patients with carbamazepine (CBZ)-induced maculopapular exanthema (MPE) to CBZ-tolerant controls. Further, the important allele was replicated by meta-analysis. Twenty-three patients with AED-induced cross-reactivity and 500 healthy individuals were enrolled from Southern China. All patients had a mild rash without mucosal or systemic involvement. The HLA-B^*13:01 allele was present in 34.78% (8/23) of patients, 14.60% (73/500) of healthy individuals, and 14.5% (763/5,270) healthy individuals, revealing a significant association (8/23 vs. 73/500; P = 0.02; OR: 3.12; 95% CI: 1.28–7.62; 8/23 vs. 763/5,270; P = 0.014; OR: 3.15; 95% CI: 1.33–7.46). HLA-B^*13:01 was presented numerically higher in CBZ-induced MPE than that in CBZ-tolerant individuals without statistical significance (33/145, 22.76%, vs. 28/179, 15.64%; P = 0.103). Meta-analysis revealed an association between HLA-B^*13:01 and cADRs induced by single AEDs or/and non-AEDs in Chinese and Thai populations (P = 0.000). This study suggests that HLA-B^*13:01 is potentially associated with AED-cADRs in general, possibly with stronger effect in cross-reactivity. Screening for HLA-B^*13:01 prior to starting AEDs therapy may help to avoid cADRs. However, this association requires further analysis in a multi-center study with a larger sample size.

Carbamazepine adverse drug reactions

INTRODUCTION

Carbamazepine (CBZ) is used for the treatment of epilepsy and other neurological and psychiatric disorders. The occurrence of adverse reactions (ADRs) to CBZ can negatively impact the quality of life of patients, as well as increase health-care costs. Thus, knowledge of CBZ-induced ADRs is important to achieve safer treatment outcomes. Areas covered: This review describes the clinical features, known mechanisms, and clinical management of the main CBZ-induced ADRs. In addition, pharmacogenetic studies focused on ADRs induced by CBZ are cited. Expert commentary: CBZ-induced ADRs are well known in the literature. The metabolite CBZ-10,11-epoxide plays an important role in the mechanism that underlies the ADRs induced by CBZ. Several factors should be considered for a safer use of CBZ, such as monotherapy prescription when possible, an adequate dose titration, knowledge of previous ADRs in the patient, and routine monitoring of CBZ plasma concentrations in symptomatic patients. Pharmacogenetics is a potential tool for CBZ therapy improvement, and the design of multicenter studies focused on the identification of biomarkers for CBZ-induced ADRs could provide useful information for a safer CBZ therapy.

HLA-DQA1, -DQB1, and -DRB1 Alleles Associated with Acute Tubulointerstitial Nephritis in a Chinese Population: A Single-Center Cohort Study

Acute tubulointerstitial nephritis (ATIN) is a common cause of acute kidney injury with various origins. HLA-DQA1, -DQB1, and -DRB1 have been associated with development of tubulointerstitial nephritis and uveitis (TINU) syndrome in case reports and small case series, but information about HLA genetic susceptibility to drug hypersensitivity-related ATIN (D-ATIN) or other types of ATIN is limited. In this article, we genotyped 154 patients with ATIN of different causes and 200 healthy controls at HLA-DQA1, -DQB1, and -DRB1 loci. We found that there was no difference between patients with D-ATIN and TINU in the carrier's frequency of HLA-DQA1, -DQB1, or -DRB1 Patients with Sjogren's syndrome-ATIN and IgG4-related ATIN presented a different pattern of tested HLA alleles. HLA-DQA1*0104 (p value corrected by false discovery rate method [Pc] = 4.72 × 10^-22, odds ratio [OR] = 13.81), -DQB1*0503 (Pc = 1.95 × 10^-14, OR = 9.51), and -DRB1*1405 (Pc = 8.06 × 10^-19, OR = 12.80) were significant risk alleles for the occurrence of D-ATIN and TINU. There were no significant associations between tested HLA alleles and ATIN induced by other causes. Patients with D-ATIN/TINU carrying HLA-DQA1*0104/DQB1*0503/DRB1*1405 had higher peak serum creatinine and more severe renal tubulointerstitial inflammatory impairment. They also had significantly higher levels of tubular HLA-DR and HLA-DQ expression, which were correlated with the numbers of interstitial CD4⁺ T lymphocytes (r = 0.975, p < 0.001 and r = 0.832, p = 0.005, respectively) and monocytes/macrophages (r = 0.721, p = 0.004 and r = 0.615, p = 0.02, respectively). In conclusion, patients with D-ATIN or TINU have genetic susceptibility in HLA-DQA1, -DQB1, and -DRB1 alleles. HLA-DQA1*0104/DQB1*0503/DRB1*1405 serves as a significant risk haplotype for development of D-ATIN and TINU, which might facilitate renal tubulointerstitial inflammation by enhancing Ag-presenting capacity of renal tubular cells.

HLA-A*02:07 Allele Associates with Clarithromycin-Induced Cutaneous Adverse Drug Reactions in Chinese Patients

Genetic risk factors could cause cutaneous adverse drug reactions (cADRs) in patients after treatment with clarithromycin. This study explored the association of HLA class I genes with clarithromycin-cADRs in Han Chinese patients. A total of 12 clarithromycin-cADR patients and 34 clarithromycin-tolerant controls were recruited for the high-resolution genotyping of HLA class I genes (HLA-A, HLA-B and HLA-C). The population controls consisted of 283 Han Chinese retrieved from the MHC database for validated comparison. A molecular docking analysis of HLA-A*02:07 protein and clarithromycin was conducted using glide module with Schrödinger Suite. Among all tested HLA alleles, the carrier frequencies of HLA-A*02:07 (58% versus 5.9%, OR = 22.40, 95% CI = 3.58-139.98, p = 8.20 × 10E-5, pc = 1.1 × 10E-3) and HLA-B*46:01 (50% versus 5.9%, OR = 16.00, 95% CI = 2.59-98.99, p = 0.002, pc = 0.03) were significantly higher in clarithromycin-cADRs than in clarithromycin-tolerant controls. However, when compared to population controls, only HLA-A*02:07, and not HLA-B*46:01, reached statistical significance (58% versus 15.5%, OR = 7.61, 95% CI = 2.31-25.04, p = 1.2 × 10E-4, pc = 1.7 × 10E-3). Furthermore, molecular docking data revealed that clarithromycin could bind to and interact with HLA-A*02:07 in two possible binding situations. These data suggest that HLA-A*02:07 might be a genetic risk factor for developing clarithromycin-cADRs in Han Chinese and serve as a useful biomarker for personalized medicine to prevent clarithromycin-cADRs.

Interethnic variability of pharmacogenetic biomarkers in Mexican healthy volunteers: a report from the RIBEF (Ibero-American Network of Pharmacogenetics and Pharmacogenomics)

Mexico presents a complex population diversity integrated by Mexican indigenous (MI) (7% of Mexico's population) and Mexican mestizos (MMs). This composition highlights the importance of pharmacogenetic studies in Mexican populations. The aims of this study were to analyze the reported frequencies of the most relevant pharmacogenetic biomarkers and metabolic phenotypes in healthy volunteers from Mexican populations and to assess its interethnic variability across MI and MM populations. After a literature search in PubMed, and according to previously defined inclusion criteria, 63 pharmacogenetic studies performed in Mexican healthy volunteers up to date were selected. These reports comprised 56,292 healthy volunteers (71.58% MM). Allele frequencies in 31 pharmacogenetic biomarkers, from 121 searched, are described. Nine of these biomarkers presented variation within MM and MI groups. The frequencies of CYP2D6*3, *4, *5, *10, *17, *35 and *41 alleles in the MM group were different from those reported in the MI group. CYP2C9*2 and *3 alleles were more frequent in MM than in MI populations (χ2 test, p<0.05). CYP2C19*3 allele was not found in the MM or MI populations reported. For UGT1A1*28, only one study was found. HLA-A*31:01 and HLA-B*15:02 were present in some MM and MI populations. Poor metabolizers for CYP2D6 and CYP2C9 were more frequent in MM than in MI groups (χ2 test, p<0.05). Only 26% of the relevant pharmacogenetic biomarkers searched have been studied in Mexican healthy volunteers; therefore, further studies are warranted. The frequency variation of biomarkers in MM and MI populations could be important for the clinical implementation of pharmacogenetics in Mexico.

Antiepilepsy drugs and the immune system

OBJECTIVE

To alert physicians about the peculiar adverse effects of antiepilepsy drugs (AEDs) on the immune system.

DATA SOURCES

PubMed literature during the past 25 years.

STUDY SELECTIONS

Reports and review articles on the hypersensitivities of AEDs and their effect on immunity.

RESULTS

AEDs have significant effects on the immune system in the form of hypersensitivity or immune suppression. IgE-mediated reactions can be urticaria, angioedema, bronchospasm, or anaphylaxis. Non-IgE-mediated reactions, more commonly associated with aromatic AEDs, can be in the form of nonspecific rashes or serious reactions, such as Stevens-Johnson syndrome, toxic epidermal necrolysis, drug rash with eosinophilia and systemic symptom syndrome, and acute generalized exanthematous pustulosis. Because of strong genetic predispositions for certain AEDs in causing severe reactions, HLA analysis before initiation of the drug is advised in certain populations. Immunoglobulin levels can be reduced to various degrees, particularly by carbamazepine, valproate, phenytoin, levetiracetam, zonisamide, and lamotrigine. Spontaneous return to normal levels can be rapid or take months to a few years, and intravenous immunoglobulin supplementation may be needed. Cellular effects can be in the form of cytopenias, inhibition of lymphocyte function, or cytokine dysregulation.

CONCLUSION

When prescribing AEDs, physicians should pay special attention to their potential adverse effects on immunity or hypersensitivity, which can be severe and even fatal. For early recognition and intervention, monitoring such patients is necessary. The cornerstone of management is discontinued use of the suspected medication and avoidance of drugs of similar structure, particularly among members of the aromatic group.

An update on HLA alleles associated with adverse drug reactions

Adverse drug reactions (ADRs) are considered as an important cause of morbidity and mortality. The hypersensitivity reactions are immune-mediated ADRs, which are dose-independent, unpredictable and have been associated with several HLA alleles. The present review aimed to describe HLA alleles that have been associated with different ADRs in populations worldwide, the recommendations of regulatory agencies and pharmacoeconomic information and databases for the study of HLA alleles in pharmacogenetics. A systematic search was performed in June 2016 of articles relevant to this issue in indexed journals and in scientific databases (PubMed and PharmGKB). The information of 95 association studies found was summarized. Several HLA alleles and haplotypes have been associated with ADRs induced mainly by carbamazepine, allopurinol, abacavir and nevirapine, among other drugs. Years with the highest numbers of publications were 2013 and 2014. The majority of the reports have been performed on Asians and Caucasians, and carbamazepine was the most studied ADR drug inducer. Two HLA alleles' databases are described, as well as the recommendations of the U.S. Food and Drug Administration, the European Medicine Agency and the Clinical Pharmacogenetics Implementation Consortium. Pharmacoeconomic studies on this issue are also mentioned. The strongest associations remain for HLA-B*58:01, HLA-B*57:01, HLA-B*15:02 and HLA-A*31:01 but only in certain populations; therefore, studies on different ethnic groups would be useful. Due to the improvement of drug therapy and the economic benefit that HLA screening represents, investigations on HLA alleles associated with ADR should continue.

HLA-A*02 alleles are associated with tetanus antitoxin-induced exanthematous drug eruptions in Chinese patients

OBJECTIVE

Tetanus antitoxin (TAT) is an effective antitetanus medicine, but may sometimes cause adverse drug reactions such as rapid-onset anaphylactic shock and late-onset cutaneous adverse drug reactions, including exanthematous drug eruptions (EDE). Human leukocyte antigen (HLA) class I alleles are strongly associated with different types of cutaneous adverse drug reactions. This study aimed to assess whether there is an association between TAT-induced EDE and HLA-A, HLA-B, and HLA-C alleles in the Chinese Han population.

PATIENTS AND METHODS

We carried out an association study in 15 patients with TAT-induced EDE and two groups of general Han Chinese patients. Allele-level genotypes of the HLA-A, HLA-B, and HLA-C genes of each patient were determined using the PCR-sequence-specific oligonucleotides method.

RESULTS

The carrier frequency of HLA serotype A2 was significantly higher in the TAT-induced EDE patients than in the general Han Chinese study participants from the human major histocompatibility complex database [n=283, odds ratio (OR)=6.93; P=0.0061]. Particularly, the carrier frequency of three A2 alleles, including HLA-A*02:01, HLA-A*02:06, and HLA-A*02:07, is significantly higher than that of the control group (OR=14.40; P=2.4×10). Furthermore, HLA-B*39:01 was in complete linkage disequilibrium with HLA-A*02:06 in the case patients. Consequently, the distribution of the HLA-A*02:06/-B*39:01 haplotype was also significantly different in the cases and the controls (OR=105.00; P=0.0024).

CONCLUSION

The HLA-A*02:06/-B*39:01 haplotype is a potential genetic marker for the TAT-induced EDE. Furthermore, the HLA-A2 serotype, especially three alleles A*02:01, A*02:06, and A*02:07, was identified to be associated with the TAT-induced EDE in the Han Chinese population for the first time.

Cutaneous Adverse Drug Reactions to Lamotrigine and Human Leukocyte Antigen Typing in North Indian Patients: A Case Series

Cutaneous adverse drug reaction (cADR) has limited epidemiological data in India. The older antiepileptic drugs, i.e., carbamazepine, phenytoin, valproic acid, phenobarbitone, etc., induce severe cADRs that have a strong associated with human leukocyte antigen (HLA)-related genetic risk factors. There is also evidence of association of certain HLA alleles with lamotrigine (LTG)-induced cADRs, but this has not been reported in the Indian population. Here, we report case series of three patients with LTG-induced “Stevens-Johnson syndrome (SJS).” Their HLA-B typing was also performed which showed the presence of HLA-B*15:02 in one case with SJS.

Significant HLA class I type associations with aromatic antiepileptic drug (AED)-induced SJS/TEN are different from those found for the same AED-induced DRESS in the Spanish population

Aromatic antiepileptic drugs (AEDs) are among the drugs most frequently involved in severe cutaneous adverse reactions (SCARs), such as Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), and drug reactions with eosinophilia and systemic symptoms (DRESS). This study investigated the associations between the genetic polymorphisms of HLA class-I and AED-induced SCARs in the Spanish population. HLA class-I genotypes were determined in AED (phenytoin[PHT],lamotrigine[LTG],carbamazepine[CBZ],phenobarbital[PB])-induced SJS/TEN (n=15) or DRESS (n=12) cases included in the Spanish SCAR registry, PIELenRed. There were 3 control groups: (A)tolerant to a single AED, (B)tolerant to any AED, and (C)Spanish population controls. For SJS/TEN, concomitant HLA-A*02:01/Cw15:02 alleles were significantly associated with PHT-cases compared to control groups B and C [(B)odds ratio(OR):14.75, p=0.009;(C)OR:27.50, p<0.001], and were close to significance with respect to control group A (p=0.060). The genotype frequency of the HLA-B*38:01 was significantly associated with PHT-LTG-cases compared with the 3 groups of controls [(A)OR:12.86, p=0.012;(B)OR:13.81; p=0.002;(C)OR:14.35, p<0.001], and with LTG-cases [(A)OR:147.00, p=0.001;(B)OR:115.00, p<0.001;(C)OR:124.70, p<0.001]. We found the HLA-B*15:02 allele in a Spanish Romani patient with a CBZ-case. The HLA-A*11:01 was significantly associated with CBZ-cases [(A)OR:63.89, p=0.002;(B)OR:36.33, p=0.005;(C)OR:28.29, p=0.007]. For DRESS, the HLA-A*24:02 genotype frequency was statistically significant in the PHT-LTG-cases [(A)OR:22.56, p=0.003;(B)OR:23.50. p=0.001; (C)OR:33.25, p<0.001], and in the LTG-cases [(A),OR:49.00, p=0.015;(B)OR:27.77, p=0.005; (C)OR:34.53, p=0.002]. HLA-A*31:01 was significantly associated with the CBZ-cases [(A)OR:22.00, p=0.047;(B)OR:29.50, p=0.033;(C)OR:35.14, p=0.006]. In conclusion, we identified several significant genetic risk factors for the first time in the Spanish Caucasian population: HLA-A*02:01/Cw*15:02 combination as a risk factor for PHT-induced SJS/TEN, HLA-B*38:01 for LTG- and PHT- induced SJS/TEN, HLA-A*11:01 for CBZ-induced SJS/TEN, and HLA-A*24:02 for LTG- and PHT- induced DRESS. The strong association between HLA*31:01 and CBZ-DRESS in Europeans was confirmed in this study.

Pharmacogenetics and ethnicity: relevance for clinical implementation, clinical trials, pharmacovigilance and drug regulation in Latin America

Congress of Pharmacogenetics and Personalized Medicine. Ethnicity, clinical implementation and regulatory environment (MESTIFAR 2016 Quito) Quito, Ecuador, 19-21 May 2016. The Ibero-American Network of Pharmacogenetics and Pharmacogenomics (RIBEF) was created in 2006 with the main aim of promoting personalized medicine and collaborative pharmacogenetics research in Spanish- and Portuguese-speaking countries in America and the Iberian Peninsula. The final goal of this initiative was the inclusion of Latin American populations that may benefit from the implementation of personalized medicine in drug therapy. Several initiatives have been promoted including the MESTIFAR project, which aimed to analyze the ethnicity, genotype and/or metabolic phenotype in Ibero-American populations. To date, 6060 healthy volunteers have been analyzed; among them, 2571 were admixed, 1824 were Caucasians, 1395 were Native Americans, 174 were Jews and 96 were Afro-descendants. Due to the large genetic variability within Latin Americans, ethnicity may be a relevant factor for the clinical implementation of personalized medicine. Moreover, the present status of clinical implementation and the future perspectives of pharmacogenetics, pharmacovigilance and clinical trials for drug regulation in Latin America compared with the EMA-Pharmacogenomics Working Party and the US FDA initiatives were analyzed.

Do HLA-A markers predict skin-reactions from aromatic antiepileptic drugs in a Norwegian population? A case control study

PURPOSE

Cutaneous adverse reactions (cADRs) from carbamazepine (CBZ) have been associated with human leukocyte antigens (HLA). Our aims were to assess the clinical usefulness of HLA-A*31:01 as a predictor of CBZ-induced cADRs in the Norwegian population and to explore whether cADRs from aromatic antiepileptic drugs (AEDs) in general might be linked with a common HLA-A-marker.

MATERIALS AND METHODS

86 ethnic Norwegians with a history of non-bullous cADRs from aromatic AEDs were included. 114 subjects tolerant to at least one aromatic AED were used as drug-specific controls. Complete HLA-A genotyping was performed. 1026 blood donors were used as population controls.

RESULTS

Comparing all cADR subjects with controls and blood donors, there were no statistical differences for any HLA-A allele, except for HLA-A*24 (p=0.022 vs. controls and p=0.014 vs. blood donors). When comparing tolerant controls with patients having had a cADR to one of the two most used drugs, CBZ (n=48) and lamotrigine (n=28), we found no significant associations for CBZ to HLA-A*31:01 or HLA-A*24:02, but for lamotrigine there was an association with HLA-A*24:02 (p=0.027). In patients developing cross-reactivity (n=14) to aromatic AEDs, the presence of HLA-A*31:01 or HLA-A*24:02 was not different compared to patients with a single cARD tolerant to at least one other drug.

CONCLUSION

We question the clinical usefulness of HLA-A*31:01 as a marker for CBZ rash in the Norwegian population. A previously suggested protective effect of aromatic AED cross-reactivity from HLA-A*24:02 was not confirmed. The association between HLA-A*24:02 and lamotrigine-induced rash should be further investigated.

The HLA-A*2402/Cw*0102 haplotype is associated with lamotrigine-induced maculopapular eruption in the Korean population

The use of lamotrigine (LTG) can be limited by the occurrence of cutaneous adverse drug reactions (cADRs) that range from maculopapular eruption (MPE) to the more severe Stevens-Johnson syndrome and toxic epidermal necrolysis. A few human leukocyte antigen (HLA)-related genetic risk factors for carbamazepine-induced cADR have been identified. However, the HLA-related genetic risk factors associated with LTG-induced cADR are not yet well known. We performed HLA genotyping in 50 Korean patients with epilepsy, including 21 patients presenting LTG-induced MPE and 29 LTG-tolerant patients. A significant association between the HLA-A*2402 allele and LTG-induced MPE was identified, in comparison with the LTG-tolerant group (odds ratio [OR] 4.09, p = 0.025) and the general Korean population (OR 3.949, p = 0.005). The frequencies of the Cw*0102 or Cw*0702 alleles were significantly higher in the LTG-MPE group than in the Korean population, whereas the frequency of the A*3303 allele was lower. The coexistence of the A*2402 and Cw*0102 alleles was significantly associated with the LTG-MPE group when compared to the LTG-tolerant group (OR 7.88, p = 0.007). In addition, the Cw*0701 allele was more frequent in the LTG-tolerant group than in the Korean population. These findings suggest the presence of HLA-related genetic risk factors for LTG-induced MPE in the Korean population.

Lamotrigine induced DIHS/DRESS: Manifestations, treatment, and outcome in 57 patients

OBJECTIVE

To evaluate the clinical features, course, response to treatment, and outcome of lamotrigine induced drug-induced hypersensitivity syndrome (DIHS) or drug reaction with eosinophilia and systemic symptoms (DRESS).

METHODS

A comprehensive PubMed and Scopus search (covering the period from January 1999 through April 2014) of the English and non-English literature (with English abstract) was conducted to identify published reports of severe cutaneous adverse reactions (SCARs) associated with lamotrigine therapy.

RESULTS

This study population included 57 patients, of whom 38 (66.67%) were female and 19 (33.33%) were male. The latency period varied from 9 days to 120 days, with a mean of 27.58 ± 20.65 days. Multisystem involvement was present in 97.37% (37/38) patients. Systemic corticosteroids were administered to (61.29%) 19/31 patients. 35/38 (92.11%) patients recovered completely, one patient developed liver failure and needed liver transplant, one died from septic shock and one died from multiple organ failure.

CONCLUSIONS

We found a greater predominance of women with LTG-DIHS/DRESS, and 68.42% patients were >18 years of age. The presenting symptoms in most of patients were fever, skin rash, liver involvement, hypereosinophilia, and lymphadenopathy. Lamotrigine is associated to a rather high risk of severe cutaneous adverse reactions and to the risk of dying from such reactions, likes many other anticonvulsants. Early recognition and withdrawal of the suspected agent may avoid irreversible damage to the organs will be life saving.