HLA-B*51 Frequency in Transplant Patients and Donors.

OBJECTIVES: HLA molecules play a crucial role in transplantation. The best treatment modality in patients with end-stage renal disease is renal transplant. HLA mismatches between patients and donors can prolong time for renal transplant therapy, reduce graft survival, and increase mortality. HLA region is the most polymorphic genetic region and is essential for antigen presentation. The main target of the recipient's immune system is HLA molecules on the surface of donor cells. HLA-B*51 is associated with Behcet disease, a rare multisystemic disease characterized by autoimmunity and inflammatory processes. In transplant recipients, inflammation and vasculitis are immunologic mechanisms that are responsible for damage of graft tissue. In this retrospective study, we aimed to investigate the frequency of HLA-B*51 in patients diagnosed with end-stage renal disease and in controls and to investigate correlations with rejection episodes. MATERIALS AND METHODS: Patients who applied to Baskent University Adana Dr. Turgut Noyan Research and Medical Center (between 2010 and 2022) with end-stage renal disease (n = 1732) and a control group (n = 5277) received HLA typing for class I (HLA-A, HLA-B). Sequence-specific primers or sequencespecific oligonucleotides were used. Among patients diagnosed with end-stage renal disease, 321 had kidney transplant. RESULTS: Frequency of HLA-B*51 was 25.92% in patients and 25.22% in controls. No significant differences were found between patients and controls in the frequency of HLA-B*51. Among kidney transplant recipients with HLA-B*51 (n = 72), 38.89% had rejection episodes and 61.11% had no rejection. No significant association was found between HLA-B*51 allele positivity and rejection. CONCLUSIONS: No significant relationship was shown between patients diagnosed with end-stage renal disease and HLA-B*51 positivity. Previous studies support frequency of the HLA-B*51 allele in the control group. Although Behçet disease is known to cause renal vasculitis, HLA-B*51 positivity alone was not associated with vasculitis or inflammation.

Case of elderly onset possible neuro-Behçet's disease with HLA-B51 homozygosity.

Behçet's disease commonly affects 20-40-year-old men and shows ophthalmo-dermatological manifestations. Here, we report a man in his 70s with acute onset of dysarthria, dysphagia and hemiplegia showing brainstem and subcortical lesions, which responded to steroid and colchicine therapy. He had a history of uveitis and was homozygous for the human leucocyte antigen-B51 allele, and we clinically diagnosed him with acute neuro-Behçet's disease. Old-age onset neuro-Behçet's disease is uncommon, and as far as we know, this is the oldest case of the first attack of neuro-Behçet's disease. Clinicians should consider Behçet's disease even for elderly patients.

Significance of HLA-B[*]51 allele expression in Crohn's disease: a case-control study.

OBJECTIVES: Crohn's disease (CD) and Behçet's disease (BD) are two autoinflammatory diseases that share clinical and pathogenic features. Furthermore, when BD involves the gastrointestinal tract, it is extremely difficult to distinguish endoscopic lesions from CD lesions. HLA-B*51 allele expression is highly associated with BD diagnosis. In this study we analysed HLA-B*51 status in 70 Argentine patients with confirmed CD diagnosis and compared it to our previous Argentine BD cohort, with the aim of finding similarities or differences between these two diseases regarding HLA-B*51 status. METHODS: This is a multi-centre case-control study, including 70 patients with confirmed CD diagnosis, who underwent HLA-B*51 allele status testing; the results were compared to our previous BD cohort of 34 patients. RESULTS: Among patients with CD, 12.85% were positive for the HLA-B*51 allele, compared with 38.24% patients with BD (OR=0.238; 95% CI=0.089-0.637; p=0.004). CONCLUSIONS: Our finding suggests that determination of HLA-B*51 allele status may contribute to the differential diagnosis between CD and BD.

Behçet's disease risk-variant HLA-B51/ERAP1-Hap10 alters human CD8 T cell immunity.

OBJECTIVES: The endoplasmic reticulum aminopeptidase (ERAP1) haplotype Hap10 encodes for a variant allotype of the endoplasmic reticulum (ER)-resident peptide-trimming aminopeptidase ERAP1 with low enzymatic activity. This haplotype recessively confers the highest risk for Behçet's diseases (BD) currently known, but only in carriers of HLA-B*51, the classical risk factor for the disease. The mechanistic implications and biological consequences of this epistatic relationship are unknown. Here, we aimed to determine its biological relevance and functional impact. METHODS: We genotyped and immune phenotyped a cohort of 26 untreated Turkish BD subjects and 22 healthy donors, generated CRISPR-Cas9 ERAP1 KOs from HLA-B*51 + LCL, analysed the HLA class I-bound peptidome for peptide length differences and assessed immunogenicity of genome-edited cells in CD8 T cell co-culture systems. RESULTS: Allele frequencies of ERAP1-Hap10 were similar to previous studies. There were frequency shifts between antigen-experienced and naïve CD8 T cell populations of carriers and non-carriers of ERAP1-Hap10 in an HLA-B*51 background. ERAP1 KO cells showed peptidomes with longer peptides above 9mer and significant differences in their ability to stimulate alloreactive CD8 T cells compared with wild-type control cells. CONCLUSIONS: We demonstrate that hypoactive ERAP1 changes immunogenicity to CD8 T cells, mediated by an HLA class I peptidome with undertrimmed peptides. Naïve/effector CD8 T cell shifts in affected carriers provide evidence of the biological relevance of ERAP1-Hap10/HLA-B*51 at the cellular level and point to an HLA-B51-restricted process. Our findings suggest that variant ERAP1-Hap10 partakes in BD pathogenesis by generating HLA-B51-restricted peptides, causing a change in immunodominance of the ensuing CD8 T cell response.

Transcriptome analysis of immune cells from Behçet's syndrome patients: the importance of IL-17-producing cells and antigen-presenting cells in the pathogenesis of Behçet's syndrome.

BACKGROUND: Behçet's syndrome (BS) is an immune-mediated disease characterized by recurrent oral ulcers, genital ulcers, uveitis, and skin symptoms. HLA-B51, as well as other genetic polymorphisms, has been reported to be associated with BS; however, the pathogenesis of BS and its relationship to genetic risk factors still remain unclear. To address these points, we performed immunophenotyping and transcriptome analysis of immune cells from BS patients and healthy donors. METHODS: ImmuNexUT is a comprehensive database consisting of RNA sequencing data and eQTL database of immune cell subsets from patients with immune-mediated diseases and healthy donors, and flow cytometry data and transcriptome data from 23 BS patients and 28 healthy donors from the ImmuNexUT study were utilized for this study. Differential gene expression analysis and weighted gene co-expression network analysis (WGCNA) were performed to identify genes associated with BS and clinical features of BS. eQTL database was used to assess the relationship between genetic risk factors of BS with those genes. RESULTS: The frequency of Th17 cells was increased in BS patients, and transcriptome analysis of Th17 cells suggested the activation of the NFκB pathway in Th17 cells of BS patients. Next, WGCNA was used to group genes into modules with similar expression patterns in each subset. Modules of antigen-presenting cells were associated with BS, and pathway analysis suggested the activation of antigen-presenting cells of BS patients. Further examination of genes in BS-associated modules indicated that the expression of YBX3, a member of a plasmacytoid dendritic cell (pDC) gene module associated with BS, is influenced by a BS risk polymorphism, rs2617170, in pDCs, suggesting that YBX3 may be a key molecule connecting genetic risk factors of BS with disease pathogenesis. Furthermore, pathway analysis of modules associated with HLA-B51 indicated that the association of IL-17-associated pathways in memory CD8+ T cells with HLA-B51; therefore, IL-17-producing CD8+ T cells, Tc17 cells, may play a critical role in BS. CONCLUSIONS: Various cells including CD4+ T cells, CD8+ T cells, and antigen-presenting cells are important in the pathogenesis of BS. Tc17 cells and YBX3 may be potential therapeutic targets in BS.

HLA-B51 Impact on Clinical Symptoms in Behcet's Disease.

OBJECTIVE: To investigate the association of HLA-B51-positivity to clinical manifestations of Behçet's disease (BD). STUDY DESIGN: Descriptive study. PLACE AND DURATION OF STUDY: Clinic of Rheumatology, Diskapi Education and Research Hospital, Health Sciences University, Turkey, from December 2018 to December 2020. METHODOLOGY: Patients who had HLA-B5 genetic results and fulfilled the international criteria for BD were included in the study. HLA-B51 status was determined and compared with the symptomatology. RESULTS: Mean age of 204 cases was 39.9±11.4 years. There were 52.5% female and 47.5% male patients. One hundred (61.7%) patients were HLA-B51-positive. The frequency of papulopustular lesions (PPL), ocular involvement, neurologic involvement, and vascular involvement was significantly higher in HLA-B51-positive patients compared to HLA-B51 negative patients (p=0.044, 0.012, 0.039, and 0.022 respectively). HLA-B51-positivity was found to be a significant risk factor for PPL (OR and 95% CI:1.946 and 1.044-3.629), ocular involvement (OR and 95% CI:2.399 and 1.165-4.938), and neurological involvement (OR and 95% CI:5.404 and 1.119-26.093). Significant risk factors for vascular involvement were male gender (OR and 95% CI:2.810 and 1.403-5.627) and low age of disease onset (OR and 95% CI:0.935 and 0.894-0.979). CONCLUSION: Ocular, vascular, and neurological involvements are more common in patients with BD with HLA-B51-positive. HLA-B51 was found to be an independent risk factor for papulopustular lesion, ocular and neurological involvement, while the male gender was found to be an independent risk factor for vascular involvement. KEY WORDS: Behcet syndrome / genetics, HLA-B51, Neurologic involvement, Ocular involvement, Vascular involvement, Vasculitis* / diagnosis.

HLA-C*04:01 Affects HLA Class I Heterozygosity and Predicted Affinity to SARS-CoV-2 Peptides, and in Combination With Age and Sex of Armenian Patients Contributes to COVID-19 Severity.

The novel SARS-CoV-2 coronavirus infection has become a global health concern, causing the COVID-19 pandemic. The disease symptoms and outcomes depend on the host immunity, in which the human leukocyte antigen (HLA) molecules play a distinct role. The HLA alleles have an inter-population variability, and understanding their link to the COVID-19 in an ethnically distinct population may contribute to personalized medicine. The present study aimed at detecting associations between common HLA alleles and COVID-19 susceptibility and severity in Armenians. In 299 COVID-19 patients (75 asymptomatic, 102 mild/moderate, 122 severe), the association between disease severity and classic HLA-I and II loci was examined. We found that the advanced age, male sex of patients, and sex and age interaction significantly contributed to the severity of the disease. We observed that an age-dependent effect of HLA-B*51:01 carriage [odds ratio (OR)=0.48 (0.28-0.80), Pbonf <0.036] is protective against severe COVID-19. Contrary, the HLA-C*04:01 allele, in a dose-dependent manner, was associated with a significant increase in the disease severity [OR (95% CI) =1.73 (1.20-2.49), Pbonf <0.021] and an advancing age (P<0.013). The link between HLA-C*04:01 and age was secondary to a stronger association between HLA-C*04:01 and disease severity. However, HLA-C*04:01 exerted a sex-dependent differential distribution between clinical subgroups [females: P<0.0012; males: P=0.48]. The comparison of HLA-C*04:01 frequency between subgroups and 2,781 Armenian controls revealed a significant incidence of HLA-C*04:01 deficiency in asymptomatic COVID-19. HLA-C*04:01 homozygous genotype in patients blueprinted a decrease in heterozygosity of HLA-B and HLA class-I loci. In HLA-C*04:01 carriers, these changes translated to the SARS-CoV-2 peptide presentation predicted inefficacy by HLA-C and HLA class-I molecules, simultaneously enhancing the appropriate HLA-B potency. In patients with clinical manifestation, due to the high prevalence of HLA-C*04:01, these effects provided a decrease of the HLA class-I heterozygosity and an ability to recognize SARS-CoV-2 peptides. Based on our observations, we developed a prediction model involving demographic variables and HLA-C*04:01 allele for the identification of potential cases with the risk of hospitalization (the area under the curve (AUC) = 86.2%) or severe COVID-19 (AUC =71%).

A comprehensive overview on the genetics of Behçet's disease.

Behçet's disease (BD) is a systemic and inflammatory disease, characterized mainly by recurrent oral and genital ulcers, eye involvement, and skin lesions. Although the exact etiopathogenesis of BD remains unrevealed, a bulk of studies have implicated the genetic contributing factors as critical players in disease predisposition. In countries along the Silk Road, human leukocyte antigen (HLA)-B51 has been reported as the strongest genetically associated factor for BD. Genome-wide association studies, local genetic polymorphism studies, and meta-analysis of combined data from Turkish, Iranian, and Japanese populations have also identified new genetic associations with BD. Among these, other HLA alleles such as HLA-B*15, HLA-B*27, HLA-B*57, and HLA-A*26 have been found as independent risk factors for BD, whereas HLA-B*49 and HLA-A*03 are independent protective alleles for BD. Moreover, other genes have also reached the genome-wide significance level of association with BD susceptibility, including IL10, IL23R-IL12RB2, IL12A, CCR1-CCR3, STAT4, TNFAIP3, ERAP1, KLRC4, and FUT2. Also, several rare nonsynonymous variants in TLR4, IL23R, NOD2, and MEFV genes have been reported to be involved in BD pathogenesis. According to genetic determinants in the loci outside the MHC region that are contributed to the host defense, immunity, and inflammation pathways, it is suggested that immune responses to the pathogen as an important environmental factor and mucosal immunity contribute to BD susceptibility.

The association of Behçet's syndrome with HLA-B51 as understood in 2021.

PURPOSE OF REVIEW: To discuss clinical and pathogenic roles of HLA-B∗51 in Behçet's syndrome. RECENT FINDINGS: HLA-B∗51 remains the most important genetic factor in Behçet's syndrome, despite the recent identification of several susceptibility genes. The prevalence of HLA-B∗51 has been shown to differ among phenotype-based clinical clusters in the same patient population. HLA-B∗51 shows epistatic interaction with the susceptible allele of endoplasmic reticulum aminopeptidase (ERAP)1 encoding the Hap10 allotype, which has the lowest trimming activity of the MHC-Class I binding peptides. Subsequent molecular studies have suggested that the disease-associated Hap10 allotype is implicated in the generation and selection of the disease protective or promoting peptides loading onto HLA-B∗51, although these pathogenic peptides have yet to be identified. SUMMARY: HLA-B∗51 is a hallmark of Behçet's syndrome but genetic markers are not very useful in the diagnosis of Behçet's syndrome. Rather, it is considered an important factor in determining clinical phenotypes in this heterogeneous condition. The epigenetic interaction of HLA-B∗51 with ERAP1 sheds light on pathogenesis.

ERAP1 Controls the Interaction of the Inhibitory Receptor KIR3DL1 With HLA-B51:01 by Affecting Natural Killer Cell Function.

The endoplasmic reticulum aminopeptidase ERAP1 regulates innate and adaptive immune responses by trimming peptides for presentation by major histocompatibility complex (MHC) class I molecules. Previously, we have shown that genetic or pharmacological inhibition of ERAP1 on murine and human tumor cell lines perturbs the engagement of NK cell inhibitory receptors Ly49C/I and Killer-cell Immunoglobulin-like receptors (KIRs), respectively, by their specific ligands (MHC class I molecules), thus leading to NK cell killing. However, the effect of ERAP1 inhibition in tumor cells was highly variable, suggesting that its efficacy may depend on several factors, including MHC class I typing. To identify MHC class I alleles and KIRs that are more sensitive to ERAP1 depletion, we stably silenced ERAP1 expression in human HLA class I-negative B lymphoblastoid cell line 721.221 (referred to as 221) transfected with a panel of KIR ligands (i.e. HLA-B*51:01, -Cw3, -Cw4 and -Cw7), or HLA-A2 which does not bind any KIR, and tested their ability to induce NK cell degranulation and cytotoxicity. No change in HLA class I surface expression was detected in all 221 transfectant cells after ERAP1 depletion. In contrast, CD107a expression levels were significantly increased on NK cells stimulated with 221-B*51:01 cells lacking ERAP1, particularly in the KIR3DL1-positive NK cell subset. Consistently, genetic or pharmacological inhibition of ERAP1 impaired the recognition of HLA-B*51:01 by the YTS NK cell overexpressing KIR3DL1*001, suggesting that ERAP1 inhibition renders HLA-B*51:01 molecules less eligible for binding to KIR3DL1. Overall, these results identify HLA-B*51:01/KIR3DL1 as one of the most susceptible combinations for ERAP1 inhibition, suggesting that individuals carrying HLA-B*51:01-like antigens may be candidates for immunotherapy based on pharmacological inhibition of ERAP1.

Clinical phenotypes of Behçet's syndrome in a large cohort of Italian patients: focus on gender differences.

Objective: The aim of this study was to investigate the clinical phenotypes of Italian patients with Behçet's syndrome (BS) according to gender. BS is a rare chronic multisystemic disorder with a wide spectrum of clinical manifestations. Human leucocyte antigen (HLA)-B51, gender, and ethnicity have been suggested as factors that could influence the clinical manifestations in BS patients. To date, few data assessing gender differences in Italian BS patients are available in the literature.Method: We retrospectively evaluated a group of Italian patients seen consecutively at our dedicated tertiary centre from 1 January 2000 to 31 May 2018. Demographics, clinical features during follow-up, and HLA status were obtained from a review of medical records and analysed in male and female groups.Results: In total, 285 [168 male (M) and 117 female (F)] patients were eligible for the study. Males had papulopustolar lesions, posterior uveitis, and deep venous thrombosis more often than females (83.3% M vs 46.2% F, 36.9% M vs 18.8% F, and 8.3% M vs 0.9% F, respectively; p < 0.01). Erythema nodosum (59.0% F vs 41.1% M; p < 0.01) and arthralgia (52.1% F vs 31.6% M; p < 0.01) were more frequent in females. No differences were found in HLA-B51 status (59.2% M vs 59.0% F).Conclusion: In our Italian cohort, BS was slightly more prevalent in males. Some gender-related differences were observed when comparing male and female cohorts. The data also confirmed that BS tends to be less aggressive in Italian female patients.

HLA-A26 is a risk factor for Behçet's disease ocular lesions.

BACKGROUND: How HLA-A26 modulates Behçet's disease (BD) ocular lesions such as iridocyclitis and retinochorioiditis has not been scrutinized. METHODS: Ministry of Health, Labour and Welfare of Japan provided us a database of BD patients who were registered from 2003 to 2014. We selected patients who satisfied International Criteria for BD and whose data for HLA-A26 was available. RESULTS: Eligible 557 patients consisting of 238 men (42.7%) and 319 women (57.3%), whose median age was 38 years old (interquartile range 29-47) were analyzed. Prevalence of general ocular lesions, iridocyclitis, retinochorioiditis, and chronic lesions were 43.1%, 30.7%, 34.1%, and 17.4%, respectively. The prevalence of ocular lesions was higher among HLA-A26 carriers compared to that among HLA-A26 non-carriers with odds ratio (OR) of 2.5 (95% confidence interval (95% CI) 1.8-3.5, p < .001) for general ocular lesions, OR of 2.5 (95% CI 1.7-3.6, p < .001) for iridocyclitis, OR of 2.8 (95% CI 1.9-4.0, p < .001) for retinochorioiditis, and OR of 2.7 (95% CI 1.7-4.3, p < .001) for 'chronic ocular lesion following iridocyclitis or retinochorioiditis'. The HLA-A26 had a similar impact on ocular lesions between HLA-B51 positive and negative cases (Breslow-Day test, p > .05). However, the HLA-A26 had a larger impact on iridocyclitis for men compared to women (Breslow-Day test, p = .040). The male HLA-A26 carriers had higher risk of iridocyclitis with OR of 3.4 (95% CI 2.0-5.9, p < .001), while the OR for women was 1.5 (95% CI 0.9-2.6, p = .146). CONCLUSION: HLA-A26 carriers had higher risk for iridocyclitis and retinochorioiditis. However, the impact was more prominent for men.

HLA-B*51 and its main subtypes in Brazilian patients with Behçet's disease.

OBJECTIVES: This study aimed to evaluate the frequency of HLA-B*51 and its subtypes in Brazilian patients with Behçet's disease (BD) and healthy controls (HC) and to assess possible associations with disease manifestations. METHODS: A cross-sectional study with sequential BD patients and HC. HLAB*51 presence was determined by sequence-specific polymerase chain reaction (SSP-PCR) and HLA-B*51 subtypes by the Sanger sequencing method. RESULTS: Eighty-three BD patients and 258 HC were evaluated. HLA-B*51 was found in 30.1% of DB patients and in 15.5% of HC (p=0.003). The most prevalent subtypes in DB patients were HLA-B*51:01 (60.0%), HLA-B*51:08 (20.0%), HLA-B*51:22 (8.0%), HLAB* 51:29 (8.0%) and HLA-B*51:02 (4.0%), while HLA-B*51:01 (77.5%) and HLA-B*51:55 (7.5%) were the most prevalent in HC. HLA-B*51 was less frequently found in patients with neurologic involvement (8.0% vs. 29.3%; p=0.034) while HLAB*51:01 was more observed in patients with ocular involvement (93.3% vs. 60.3%; p=0.014). No BD patient with neurologic or vascular involvement presented HLA-B*51:01. HLAB*51:08 was more frequent in patients with vascular manifestations (60.0% vs. 15.4%; p=0.012). In multivariate analysis, HLA-B*51 was an independent risk factor for BD (OR=2.410; 95%CI: 1.332-4.361; p=0.004) and HLA-B*51:08 had an independent association with vascular manifestations of BD (OR = 14.843; 95%CI: 1.550 - 142.115; p=0.019). CONCLUSIONS: The prevalence of HLAB*51 is higher in Brazilian BD patients compared to HC, and it is a risk factor for BD. The HLA-B*51:08 subtype was independently associated with vascular manifestations of BD.

The HLA-B*51 allele is strongly associated with Behçet Disease in an Argentinean population / El alelo HLA-B*51 se asoció fuertemente a la Enfermedad de Behçet en la población argentina

OBJECTIVE: To assess the association between the HLA-B*51 allele and Behçet Disease (BD) in Argentinean patients. METHODS: We enrolled 34 consecutive Argentinean patients with definitive diagnosis of BD between October 2016 and March 2017. None of the patients had the HLA-B*51 allele determined at study entry. Unrelated controls (n=240) were randomly obtained from the national cadaveric donor database. Demographic and clinical features of the patients were recorded by attending physicians through a questionnaire. RESULTS: Mean age of cases was 42 years old. Nineteen (55.8%) were male, and the mean age at diagnosis was 35 years old; twenty (58.8%) were Mestizos, 8 (23.5%) were Caucasian, and 6 (17.6%) were Amerindians. Thirteen (38.2%) of 34 cases were HLA-B*51 allele positive; 11 were heterozygous and 2 homozygous for the allele. Thirty-four (14.2%) of 240 controls were positive for the HLA-B*51 allele. The association between BD and HLA-B*51 allele was greater than that of control group (OR=3.75; p = 0.0012). CONCLUSIONS: The HLA-B*51 allele is strongly associated with BD in Argentinean patients. Our finding is consistent with previous studies indicating that the HLA-B*51 allele is an important susceptibility gene in BD regardless the geographical region and ethnicity

OBJETIVO: Evaluar la asociación entre el alelo HLA-B*51 y la enfermedad de Behçet (EB) en pacientes argentinos. MÉTODOS: Incluimos en forma consecutiva 34 pacientes argentinos con diagnóstico definitivo de EB entre los meses de octubre de 2016 y marzo de 2017. Ninguno de los pacientes tenía el alelo HLA-B*51 determinado al inicio del estudio. Los controles no relacionados (n=240) se obtuvieron al azar de la base nacional de datos de donantes cadavéricos. Las características demográficas y clínicas de los pacientes fueron registradas por los médicos asistentes a través de un cuestionario. RESULTADOS: La edad promedio de los casos fue de 42 años. Diecinueve (55,8%) fueron varones, y la edad promedio en el momento del diagnóstico fue de 35 años; 20 (58,8%) fueron mestizos, 8 (23,5%) caucásicos y 6 (17,6%) amerindios. Trece (38,2%) de los 34 casos fueron positivos para el alelo HLA-B*51; 11 de ellos fueron heterocigotas y 2 homocigotas para dicho alelo. Treinta y cuatro (14,2%) de los 240 controles fueron positivos para el alelo HLA-B*51. La asociación entre la EB y el alelo HLA-B*51 fue mayor que en el grupo control (OR=3,75; p = 0,0012). CONCLUSIONES: El alelo HLA-B*51 está fuertemente asociado con la EB en pacientes argentinos. Nuestro hallazgo es consistente con estudios previos que indican que el alelo HLA-B*51 es un gen de susceptibilidad importante en la EB independientemente de la región geográfica y la etnia

Contribution of HLA-B*51:01 and -A*26:01 to Behçet's disease and their clinical association in Thai patients.

AIMS: To investigate susceptible human leukocyte antigen (HLA) alleles and their associations with clinical features in Thai patients with Behçet's disease (BD). METHOD: Eighteen HLA-A and 36 HLA-B alleles were determined in 42 Thai BD patients and 99 healthy controls (HCs) by reverse line blot assay, and reconfirmed by MICRO SSP assay. RESULTS: The BD patients had significantly higher allele frequency (AF) of HLA-B*51 than the HCs (13.10% vs 5.05%, P = .025). The AF of HLA-A*26, -A*26:01 and -B*51:01 also was higher and almost reached statistical significance (5.59% vs 1.52%, P = .054, 5.95% vs 1.52%, P = .054 and 10.71% vs 4.04%, P = .051, respectively). However, the BD patients had significantly higher AF of either HLA-A*26:01 or -B*51:01 (16.67% vs 5.56%, P = .005), or -A*26:01 or -B*51X (19.05% vs 6.56%, P = .003). The AF of HLA-B*51:01 and -B*51X increased significantly in -A*26:01 non-carrier BD patients (12.16% vs 4.17%, P = .024 and 14.86% vs 5.21%, P = .019, respectively); and that of HLA-A*26:01 was significantly higher in -B*51X non-carrier BD patients (7.58% vs 1.67%, P = .034). HLA-B*51:01 associated significantly with the presence of posterior uveitis and visual impairment (18.18% vs 2.50%, P = .031 for both conditions). HLA-B*51:01 was not observed in BD patients with gastrointestinal involvement or arthritis. Furthermore, the AF of HLA-B*51:01 was significantly higher in HLA-A*26:01 non-carrier BD patients without arthritis (17.30% vs 0%, P = .050). CONCLUSION: HLA-B*51:01 was a susceptible allele for Thai BD patients, and associated with posterior uveitis and visual impairment. HLA-A*26:01 was another susceptible allele in HLA-B*51X non-carrier patients. The protective effect of HLA-B*51:01 on arthritis needs further investigation.

The HLA-B*51 Allele is strongly associated with Behçet Disease in an Argentinean population.

OBJECTIVE: To assess the association between the HLA-B*51 allele and Behçet Disease (BD) in Argentinean patients. METHODS: We enrolled 34 consecutive Argentinean patients with definitive diagnosis of BD between October 2016 and March 2017. None of the patients had the HLA-B*51 allele determined at study entry. Unrelated controls (n=240) were randomly obtained from the national cadaveric donor database. Demographic and clinical features of the patients were recorded by attending physicians through a questionnaire. RESULTS: Mean age of cases was 42 years old. Nineteen (55.8%) were male, and the mean age at diagnosis was 35 years old; twenty (58.8%) were Mestizos, 8 (23.5%) were Caucasian, and 6 (17.6%) were Amerindians. Thirteen (38.2%) of 34 cases were HLA-B*51 allele positive; 11 were heterozygous and 2 homozygous for the allele. Thirty-four (14.2%) of 240 controls were positive for the HLA-B*51 allele. The association between BD and HLA-B*51 allele was greater than that of control group (OR=3.75; p=0.0012). CONCLUSIONS: The HLA-B*51 allele is strongly associated with BD in Argentinean patients. Our finding is consistent with previous studies indicating that the HLA-B*51 allele is an important susceptibility gene in BD regardless the geographical region and ethnicity.

HLA-B*51:01 and CYP2C9*3 Are Risk Factors for Phenytoin-Induced Eruption in the Japanese Population: Analysis of Data From the Biobank Japan Project.

CYP2C9*3 and HLA-B alleles are reportedly associated with phenytoin-induced eruption in some East Asian populations; however, this finding is not readily applicable to the Japanese population. Thus, we aimed to investigate the risk alleles using samples and data from BioBank Japan. A total of 747 patients (24 cases and 723 tolerant controls) were selected for analysis. Case-control association studies were conducted, using CYP2C9*3, CYP2C9*27, CYP2C19*2, CYP2C19*3, and HLA-B allele genotype data. CYP2C9*3 carrier status was significantly associated with phenytoin-induced eruption (P = 0.0022, odds ratio 7.05, 95% confidence interval, 2.44-20.4). HLA-B*51:01 showed the most prominent association (P = 0.010, odds ratio 3.19, 95% confidence interval, 1.37-7.48). Including both of these features improved predictive performance, measured as area under the receiver operating characteristic curve, by 10%. CYP2C9*3 and HLA-B*51:01 allele carrier statuses are significantly associated with phenytoin-induced eruption; thus, checking this carrier status before prescription would decrease the incidence of phenytoin-induced eruption in clinical practice.