HLA Alleles Research Articles

Statistically and functionally fine-mapped blood eQTLs and pQTLs from 1,405 humans reveal distinct regulation patterns and disease relevance

Studying the genetic regulation of protein expression (through protein quantitative trait loci (pQTLs)) offers a deeper understanding of regulatory variants uncharacterized by mRNA expression regulation (expression QTLs (eQTLs)) studies. Here we report cis-eQTL and cis-pQTL statistical fine-mapping from 1,405 genotyped samples with blood mRNA and 2,932 plasma samples of protein expression, as part of the Japan COVID-19 Task Force (JCTF). Fine-mapped eQTLs (n = 3,464) were enriched for 932 variants validated with a massively parallel reporter assay. Fine-mapped pQTLs (n = 582) were enriched for missense variations on structured and extracellular domains, although the possibility of epitope-binding artifacts remains. Trans-eQTL and trans-pQTL analysis highlighted associations of class I HLA allele variation with KIR genes. We contrast the multi-tissue origin of plasma protein with blood mRNA, contributing to the limited colocalization level, distinct regulatory mechanisms and trait relevance of eQTLs and pQTLs. We report a negative correlation between ABO mRNA and protein expression because of linkage disequilibrium between distinct nearby eQTLs and pQTLs.

Frequencies of Human Leukocyte Antigen Alleles in Turkish Children with Kawasaki Disease

Abstract Objective Kawasaki disease (KD) is an acute systemic vasculitis that is one of the major causes of acquired heart disease especially in young children. The pathogenesis of KD is still unclear. The increased incidence of the disease among Japanese children and siblings of affected patients suggests a genetic component to KD susceptibility. Several reports have studied human leukocyte antigen (HLA) polymorphisms in different populations with KD and found various results. In the present study, we aimed to evaluate the association of HLA-A, -B, -C, -DRB1, and -DQB1 allele frequencies in Turkish children with KD. Methods The study was conducted between January 2016 and February 2018. HLA Class I (A, B, and C) and Class II (DRB1 and DQB1) alleles of patients and healthy controls were studied using the low-resolution DNA-based sequence-specific oligonucleotide method. Results Fifty children with KD and 500 healthy controls were included in this study. In the analysis of HLA-A, HLA-B, HLA-C, and HLA-DRB1 alleles, no statistical difference was found in the frequency of alleles between the patients with KD and the control group. However, a significantly lower frequency of the HLA-DQB1*03 allele was observed in the KD group than in the control group (p < 0.001, odds ratio [OR]: 0.29, 95% confidence interval [CI]: 0.15–0.55). When the patients with KD were divided into two subgroups with or without coronary artery lesions (CALs), the frequency of the HLA-DQB1*03 allele was also found lower in the KD group with CALs than the KD group without CALs (p = 0.008, OR: 0.19, 95% CI: 0.05–0.68). Conclusion The study may guide future studies on HLA-DQB1*03 whether it is a protective allele for KD and CALs in Turkish children.

HLA A*24:02-restricted T cell receptors cross-recognize bacterial and preproinsulin peptides in type 1 diabetes.

CD8+ T cells destroy insulin-producing pancreatic β cells in type 1 diabetes through HLA class I-restricted presentation of self-antigens. Combinatorial peptide library screening was used to produce a preferred peptide recognition landscape for a patient-derived T cell receptor (TCR) that recognized the preproinsulin-derived (PPI-derived) peptide sequence LWMRLLPLL in the context of disease risk allele HLA A*24:02. Data were used to generate a strong superagonist peptide, enabling production of an autoimmune HLA A*24:02-peptide-TCR structure by crystal seeding. TCR binding to the PPI epitope was strongly focused on peptide residues Arg4 and Leu5, with more flexibility at other positions, allowing the TCR to strongly engage many peptides derived from pathogenic bacteria. We confirmed an epitope from Klebsiella that was recognized by PPI-reactive T cells from 3 of 3 HLA A*24:02+ patients. Remarkably, the same epitope selected T cells from 7 of 8 HLA A*24+ healthy donors that cross-reacted with PPI, leading to recognition and killing of HLA A*24:02+ cells expressing PPI. These data provide a mechanism by which molecular mimicry between pathogen and self-antigens could have resulted in the breaking of self-tolerance to initiate disease.

Non-inherited maternal HLA alleles detected in breast milk-contaminated buccal swabs

Non-inherited maternal HLA alleles detected in breast milk-contaminated buccal swabs

Serological reactivity of HLA alleles is dependent on race/ethnicity

Serological reactivity of HLA alleles is dependent on race/ethnicity

HLA-A, -B, -C and -DRB1 Association with Autism Spectrum Disorder Risk: A Sex-Related Analysis in Italian ASD Children and Their Siblings.

Autism Spectrum disorders (ASD) are diagnosed more often in males than in females, by a ratio of about 3:1; this is likely to be due to a difference in risk burden between the sexes and/or to "compensatory skills" in females, that may delay the diagnosis of ASD. Identifying specific risk factors for ASD in females may be important in facilitating early diagnosis. We investigated whether HLA- class I: -A, -B, -C and class II -DRB1 alleles, which have been suggested to play a role in the development of ASD, can be considered as sex-related risk/protective markers towards the ASD. We performed HLA allele genotyping in 178 Italian children with ASD, 94 healthy siblings, and their parents. HLA allele distribution was compared between children with ASD, sex-matched healthy siblings, and a cohort of healthy controls (HC) enrolled in the Italian bone marrow donor registry. Allele transmission from parents to children with ASD and their siblings was also assessed. Our findings suggest that HLA-A*02, B*38, and C*12 alleles are more frequently carried by females with ASD compared to both HC and healthy female siblings, indicating these alleles as potential risk factors for ASD in females. Conversely, the HLA-A*03 allele was more commonly transmitted to healthy female siblings, suggesting it might have a protective effect. Additionally, the HLA-B*44 allele was found to be more prevalent in boys with ASD, indicating it is a potential risk factor for male patients. This is the first Italian study of sex-related HLA association with ASD. If confirmed, these results could facilitate early ASD diagnosis in female patients, allowing earlier interventions, which are crucial in the management of neurodevelopmental disorders.

Role of HLA-B*58:01-restricted CD8+ T cells in HIV-1 subtype AE infection

Abstract HLA-B*58:01 and HLA-B*57 are protective alleles against HIV-1 subtype B or C infection whereas these HLA alleles have not been reported as protective in HIV-1 subtype AE infection. Although HLA-B*58:01-restricted and HLA-B*57-restricted HIV-1-specific CD8+ T cells have been thoroughly analyzed in subtype B or C infection, they have only been partially analyzed in subtype AE infection. We identified six HLA-B*58:01-restricted subtype AE epitopes in Vietnamese individuals infected with subtype AE. HLA-B*58:01-restricted T-cell responses to Gag epitopes, which may control disease progression in HLA-B*58:01+ and HLA-B*57+ individuals infected with subtype B or C, were not protective in subtype AE infection. These findings suggest that the loss of HLA-B*58:01-restricted T cells specific for some Gag epitopes and/or their reduced ability may account for the lack of protective effects conferred by HLA-B*58:01 in subtype AE infection.

Harmonisation of the HLA tests for the diagnosis of coeliac disease: experiences from the Czech external proficiency testing program.

Coeliac disease (CD) is an autoimmune disorder caused by the ingestion of gluten-containing grains. One of the prerequisites for the development of the disease is the presence of specific combinations of HLA alleles at the DQA1 and DQB1 loci. The HLA test is a supportive diagnostic test. In the Czech Republic, approximately 3,500 HLA tests for CD diagnosis are performed annually in almost three dozen laboratories. The HLA Department of the Institute of Haematology and Blood Transfusion in Prague has been offering the EPT "Detection of HLA Alleles Associated with Diseases" for more than 10years. The results are evaluated in terms of the correct determination of predisposing alleles/allelic groups and clinical interpretation. Every year, we notice some problems with the detection of CD-associated alleles and the interpretation of results. Annual workshops are part of this EPT, and they also include recommendations for the interpretation of results. This interpretation is evolving based on the current knowledge in the field. The current recommendation for interpretation was adopted in 2023, dividing HLA-DQA1/DQB1 genotypes into three categories: 1) detected HLA genotype is associated with predisposition to coeliac disease; 2) coeliac disease could not be excluded based on the detected HLA genotype; 3) coeliac disease could be excluded with high probability based on the detected HLA genotype. The quality of examination is increasing but still needs improvement. Correct results and accurate interpretation can inform clinicians' decisions about the diagnosis of coeliac disease in appropriate patients.

Abstract P181: Class 1 human leukocyte antigens exhibit marked variability in capacity to present isolevuglandin adducts

Introduction: Isolevuglandins (isoLGs) are lipid peroxidation products that covalently modify lysine residues on self-proteins. These modified self-proteins are processed to peptides that are presented in the context of class I major histocompatibility complexes (MHC-I). In hypertension, this modification enhances CD8 + T cell activation, contributing to inflammation and elevated blood pressure. In mice we found that IsoLG-adduct presentation is highly dependent on class I MHC structure. We sought to determine if human class I MHC (HLAs) exhibit similar variability in their ability to present these adducts by screening alleles representing 90% of the population. Hypothesis: We hypothesize that HLA subtypes exhibit variable capacity for isoLG presentation. Methods: HLA alleles representing 90% demographic frequency were identified from the US National Merit Donor Program Allele Frequency Database. HLA-null human K562 cells were transduced with these alleles, expanded, and enriched for HLA expression by flow cytometry to produce single HLA allele lines. To induce isoLG adduct presentation, cells were treated with 1mM tert-Butyl hydroperoxide (tBHP). After 24 hours, we employed Forster resonance energy transfer (FRET) between HLAs and isoLG-adducts using antibodies specific for both, which we have shown is indicative of IsoLG-adduct presentation (Fig 1A-C). Results: Substantial variability for isoLG-adduct presentation was observed between HLA subtypes A, B and C (Figure 1A-1C). Scikit-learn’s KMeans clustering revealed four patterns of isoLG-adduct presentation among HLAs: Low baseline/low activation, low baseline/high activation, intermediate baseline/intermediate activation, and high baseline/high activation alleles (Fig 1D). Conclusions: These findings identify specific HLA alleles as high isoLG presenters, potentially associated with increased immune activation risk. Combining these findings, HLA alleles, and diagnosis code databases could aid in identifying high-risk haplotypes for immune activation in human hypertension.

V-110.7: Prevalence of non- representation of HLA antigens and alleles in Single Antigen Bead assay panels in patients at a referral lab.

V-110.7: Prevalence of non- representation of HLA antigens and alleles in Single Antigen Bead assay panels in patients at a referral lab.

Genetic variants associated with immune-mediated liver injury from checkpoint inhibitors.

The clinical features, liver histology, and genetic variants in 57 patients with moderate to severe immune-mediated liver injury from checkpoint inhibitors (ILICI) are presented. Between 2010 and 2022, 57 high-causality ILICI cases were enrolled in the Drug-Induced Liver Injury Network. HLA and selected candidate gene variants were tested for association with ILICI risk compared to the general population and other DILI controls. The 57 high-causality cases were attributed to pembrolizumab (16), ipilimumab (15), ipilimumab and nivolumab (13), and other immune checkpoint inhibitors (13) and occurred at a median of 72 days after the first infusion. Median age was 57.8 years, 66% male, and 89% were non-Hispanic Whites. At DILI onset, 53% had hepatocellular, 35% mixed, and 15% cholestatic, with younger patients more likely to have hepatocellular injury. The incidence of ANA, smooth muscle antibody, and elevated IgG levels was low (17%, 23%, and 0%), but corticosteroids were given to 86%. Microgranulomas and hepatic steatosis were seen in 54% and 46% of the 26 liver biopsies, respectively. The HLA alleles associated with autoimmune hepatitis were not over-represented, but 2 host immune response genes (EDIL3 and SAMA5A) and 3 other genes (GABRP, SMAD3, and SLCO1B1) were associated with ILICI (OR: 2.08-2.4, p<0.01). ILICI typically arises within 12 weeks of initiating immunotherapy and is self-limited in most cases. Genetic variants involved in host T-cell regulation and drug disposition were identified, implicating these pathways in the pathogenesis of ILICI. If validated, these findings could lead to improved diagnostic instruments and possible treatments for ILICI.

Characterisation of the novel HLA-B*15:699 and HLA-C*03:677 alleles identified in Danish individuals.

Two novel HLA alleles HLA-B*15:699 and HLA-C*03:677 were detected during routine HLA typing by next generation sequencing.

Telomere Length, HLA, and Longevity-Results from a Multicenter Study.

Aging is an exceptionally complex process that depends on genetic, environmental, and lifestyle factors. Previous studies within the International HLA and Immunogenetics Workshop (IHIWS) component "Immunogenetics of Ageing" showed that longevity is associated with positive selection of HLA-DRB1*11- and DRB1*16-associated haplotypes, shown to be protective against diseases. Within the 18th IHIWS, we aimed to investigate the relevance of telomere length for successful aging and its association with classical HLAs. In total 957 individuals from Bulgaria, Turkey, Romania, and Poland in two age groups, elderly individuals (age 65-99 years) and ethnically matched young group (age 18-64 years), were investigated. The obtained results confirmed interpopulation differences in the distribution of HLA alleles, documented the lengths of telomeres in analyzed populations, and demonstrated significant associations of telomere length with aging as well as with the presence of some HLA class I or class II alleles. They suggest that telomere length assessment combined with HLA genotyping may help identify immunogenetic profiles associated with longevity. The associations between HLA and telomeres support the theory that HLA genes influence the aging process. However, further research is needed to clarify the biological basis of the observed relationships.

Genetic association of antinuclear antibodies with HLA in JIA patients: a Swedish cohort study

BackgroundJuvenile Idiopathic Arthritis (JIA) is a complex autoimmune disease and the most common chronic rheumatological disease affecting children under the age of 16. The etiology of JIA remains poorly understood, but evidence suggests a significant genetic predisposition.MethodsWe analyzed a Swedish cohort of 329 JIA patients and 728 healthy adult controls using the Illumina OmniExpress array for genotyping. HLA alleles were imputed from GWAS data using the SNP2HLA algorithm.ResultsCase–control analysis yielded 12 SNPs with genome-wide significant association to JIA, all located on chromosome 6 within the MHC class II gene region. Notably, the top SNP (rs28421666) was located adjacent to HLA-DQA1 and HLA-DRB1. HLA-DRB1*08:01, HLA-DQA1*04:01, and HLA-DQB1*04:02 were the haplotypes most strongly associated with an increased risk of JIA in the overall cohort. When analyzing disease specific subtypes, these alleles were associated with oligoarthritis and RF-negative polyarthritis. Within the complex linkage disequilibrium of the HLA-DRB1-DQA1-DQB1 haplotype, our analysis suggests that HLA-DRB1*08 might be the primary allele linked to JIA susceptibility. The HLA-DRB1*11 allele group was also independently associated with JIA and specifically enriched in the oligoarthritis patient group. Additionally, our study revealed a significant correlation between antinuclear antibody (ANA) positivity and specific HLA alleles. The ANA-positive JIA group showed stronger associations with the HLA-DRB1-DQA1-DQB1 haplotype, HLA-DRB1*11, and HLA-DPB1*02, suggesting a potential connection between genetic factors and ANA production in JIA. Furthermore, logistic regression analysis reaffirmed the effects of HLA alleles, female sex, and lower age at onset on ANA positivity.ConclusionsThis study identified distinct genetic associations between HLA alleles and JIA subtypes, particularly in ANA-positive patients. These findings contribute to a better understanding of the genetic basis of JIA and provide insights into the genetic control of autoantibody production in ANA-positive JIA patients. This may inform future classification and personalized treatment approaches for JIA, ultimately improving patient outcomes and management of this disease.

Non-IgE-mediated drug-induced hypersensitivity reactions in pediatrics.

Despite their prevalence and potential severity, non-IgE-mediated drug-induced hypersensitivity reactions (DHRs) are under-researched and poorly defined, particularly in children. Presentations range from mild cutaneous reactions to severe systemic diseases, with pathophysiological mechanisms and reliable diagnostic markers not well established. The lack of validated tests often leads to permanent drug restrictions, reliance on second-line drugs, and increased costs. Focusing on recent advancements and areas needing further research, this review aims to enhance children's recognition, diagnosis, and management of non-IgE-mediated DHRs. Recent studies have enhanced the understanding of immediate and delayed non-IgE-mediated drug reactions. Key findings include the Mas-related G protein-coupled receptor X2 in mast cells and the identification of HLA alleles linked to severe cutaneous adverse reactions, such as Stevens-Johnson syndrome and toxic epidermal necrolysis. Improved diagnostic techniques, including skin testing, show promise in identifying immediate and delayed non-IgE DHRs. Additionally, research highlights the impact of cofactors, drug metabolites, and co-infections on these DHRs and explores potential biomarkers for predicting reaction severity. Non-IgE-mediated DHRs are a significant cause of morbidity and treatment changes in pediatric patients. Recent research underscores their clinical presentations and mechanisms, paving the way for more precise diagnostic and therapeutic strategies to improve patient outcomes.

A synthetic cytotoxic T cell platform for rapidly prototyping TCR function

Current tools for functionally profiling T cell receptors with respect to cytotoxic potency and cross-reactivity are hampered by difficulties in establishing model systems to test these proteins in the contexts of different HLA alleles and against broad arrays of potential antigens. We have implemented a granzyme-activatable sensor of T cell cytotoxicity in a universal prototyping platform which enables facile recombinant expression of any combination of TCR-, peptide-, and class I MHC-coding sequences and direct assessment of resultant responses. This system consists of an engineered cell platform based on the immortalized natural killer cell line, YT-Indy, and the MHC-null antigen-presenting cell line, K562. These cells were engineered to furnish the YT-Indy/K562 pair with appropriate protein domains required for recombinant TCR expression and function in a non-T cell chassis, integrate a fluorescence-based target-centric early detection reporter of cytotoxic function, and deploy a set of protective genetic interventions designed to preserve antigen-presenting cells for subsequent capture and downstream characterization. Our data show successful reconstitution of the surface TCR complex in the YT-Indy cell line at biologically relevant levels. We also demonstrate successful induction and highly sensitive detection of antigen-specific response in multiple distinct model TCRs. Additionally, we monitored destruction of targets in co-culture and found that our survival-optimized system allowed for complete preservation after 24 h exposure to cytotoxic effectors. With this bioplatform, we anticipate investigators will be empowered to rapidly express and characterize T cell receptor responses, generate knowledge regarding the patterns of T cell receptor recognition, and optimize therapeutic T cell receptors.

High Resolution HLA-A, HLA-B, and HLA-C Allele Frequencies in Romanian Hematopoietic Stem Cell Donors.

The HLA genes are associated with various autoimmune pathologies, with the control of the immune response also being significant in organs and cells transplantation. The aim of the study is to identify the HLA-A, HLA-B, and HLA-C alleles frequencies in the analyzed Romanian cohort. We performed HLA typing using next-generation sequencing (NGS) in a Romanian cohort to estimate class I HLA allele frequencies up to a six-digit resolution. A total of 420 voluntary donors from the National Registry of Voluntary Hematopoietic Stem Cell Donors (RNDVCSH) were included in the study for HLA genotyping. Peripheral blood samples were taken and brought to the Fundeni Clinical Institute during 2020-2021. HLA genotyping was performed using the Immucor Mia Fora NGS MFlex kit. A total of 109 different alleles were detected in 420 analyzed samples, out of which 31 were for HLA-A, 49 for HLA-B, and 29 for HLA-C. The most frequent HLA-A alleles were HLA-A*02:01:01 (26.11%), HLA-A*01:01:01 (12.5%), HLA-A*24:02:01 (11.67%), HLA-A*03:01:01 (9.72%), HLA-A*11:01:01, and HLA-A*32:01:01 (each with 8.6%). For the HLA-B locus, the most frequent allele was HLA-B*18:01:01 (11.25%), followed by HLA-B*51:01:01 (10.83%) and HLA-B*08:01:01 (7.78%). The most common HLA-C alleles were HLA-C*07:01:01 (17.36%), HLA-C*04:01:01 (13.47%), and HLA-C*12:03:01 (10.69%). Follow-up studies are ongoing for confirming the detected results.

Model for the Study of Drug Hypersensitivity Based on Bucilamine and the HLA-DRB1*08:02 Allele in Colombian Amerindian Populations

Backgrounds: Allergic diseases and hypersensitivity reactions are common disorders that in turn consist of an extensive genetic component in which the molecules of the Major Histocompatibility Complex (MHC) are included, which have certain alleles associated with the development of hypersensitivity to certain drugs, among which is the allele HLA-DRB1 * 08: 02 as a predisposing factor of hypersensitivity to Bucillamine; this drug is the starting point for the study of the relationship between hypersensitivity reactions to medications and the expression of certain alleles of MHC. Objective: Find the relationship between hypersensitivity to the drug and the expression of the specific allele in Amerindian populations of the Sierra Nevada de Santa Marta and in turn suggest the application of the methodological model proposed in similar studies that seek to relate drug allergies with specific HLA alleles. Methods: A systematic search of information was carried out in the Sience, ScienceDirect, Elsevier and Pubmed databases, the frequencies obtained were tabulated and organized according to their expression to be analyzed with the MEGA7 software. Results: A significant frequency of the HLA-DRB1 * 08: 02 allele was found in the Ijka (61.7%), Arhuaco (41.5%), Kogi (17.9%) and Arsario (15%). Conclusion: A cautious use of Bucillamine and structurally similar drugs it’s recommended in susceptible Amerindian populations, at the same time the application of the proposed model it’s recommended for the study of different drugs that could trigger an allergic reaction based on HLA’s allele expression.

The characteristic of HLA-A, HLA-B, HLA-C, HLA-DRB1, HLA-DRB3/4/5, HLA-DQA1, HLA-DQB1, HLA-DPA1, and HLA-DPB1 alleles in Zhejiang Han population.

The Zhejiang Han population, a subgroup of the Southern Han ethnic group, resides in Zhejiang Province, situated on the southeast coast of China. In this study, we conducted HLA genotyping for 813 voluntary umbilical cord blood donors from the Zhejiang Han population, targeting 11 HLA loci, namely HLA-A, HLA-B, HLA-C, HLA-DRB1, HLA-DRB3/4/5, HLA-DQA1, HLA-DQB1, HLA-DPA1, and HLA-DPB1, using the next-generation sequencing method. Our analysis of the alleles and haplotypes revealed a high degree of polymorphism within these loci. A total of 289 unique HLA alleles were identified, with the HLA-B locus exhibiting the most significant diversity, while HLA-DRB4 displayed the lowest variation. Due to the inherent limitations of the sequencing method, some unresolvable alleles in the specific loci, such as HLA-DRB1, HLA-DPA1, and HLA-DPB1, were assigned as G group designation. In our comprehensive analysis across all 11 HLA loci, a total of 1204 haplotypes were estimated. The distribution of these alleles was similar to those of the Chinese Southern Han population while highly different from the Caucasian population. These findings contribute to a deeper understanding of the genetic characteristics of HLA loci within the Chinese Southern Han population.

Human leukocyte antigen class II (DRB1 and DQB1) alleles frequencies in patients with bullous pemphigoid, Stevens–Johnson syndrome and toxic epidermal necrolysis in Russian population

BACKGROUND: Bullous pemphigoid is known to be an autoimmune, life-threatening blistering skin disorder characterized by subepidermal blister formation. In bullous pemphigoid activation of B-cell immunity depends on the interaction between T-cell receptors and classic HLA II molecules. Similar interrelation has been revealed in a vast variety of studies on severe allergic reactions such as Stevens-Johnson syndrome and toxic epidermal necrolysis. It was also suggested that Stevens-Johnson syndrome and toxic epidermal necrolysis might be associated both with HLA I and II classes. AIM: To assess the prevalence of HLA-DRB1 and DQB1 alleles at a low and high-resolution levels in patients with bullous pemphigoid and Stevens-Johnson syndrome / toxic epidermal necrolysis. MATERIALS AND METHODS: 29 Bullous pemphigoid, 14 Stevens-Johnson syndrome / toxic epidermal necrolysis patients and 92 health volunteers were included in the study. HLA-DRB1 and DQB1 alleles were assessed by polymerase chain reaction using specific primers. RESULTS: At a low-resolution level, HLA-DRB1*4 (p 0.02) and DRB1*14 (p 0.0015) alleles were statistically significantly revealed in bullous pemphigoid patients compared to health controls. Additionally, at the high-resolution level the predisposing to bullous pemphigoid HLA-DRB1*04:02 allele was also identified (p 0.01). At the low-resolution level of HLA-DQB1 typing we displayed protective and predisposing to bullous pemphigoid alleles HLA-DQB1*1 (p 0.01) and HLA-DQB1*2 (p 0.039) respectively. At the low-resolution level of HLA-DQB1 typing, the chances to obtain DQB1*03:02 allele were 3.71 times higher compared to healthy volunteers (p 0.01). In patients with Stevens-Johnson syndrome / toxic epidermal necrolysis, HLA-DRB1*4 allele was shown to be predisposing (p 0.03). For all other types of HLA alleles (DRB1 and DQB1) at the high-resolution level no any statistically significant results have been observed in these patients. CONCLUSION: We identified HLA-DRB1*4, DRB1*14, DRB1*04:02 alleles predisposing to the development of bullous pemphigoid, with the HLA-DQB1*1 allele being protective for the development of bullous pemphigoid and HLA-DRB1*4 allele predisposing to the development of severe drug reactions of Stevens-Johnson syndrome / toxic epidermal necrolysis. No any protective alleles in Stevens-Johnson syndrome / toxic epidermal necrolysis patients were detected.