Behçet Disease and the HLA System

Association of HLA-B27 and Behcet's disease: a systematic review and meta-analysis

Background

To calculate the genetic impact of the “HLA-B27” allele on the risk of Behcet’s disease (BD) progression using a systematic review and meta-analysis on case control papers.

Methods

A systematic review search was conducted on the MeSH keywords of Behcet’s disease, HLAB27 and B27 in PubMed, Scopus, ProQuest, EMBASE, SID, Magiran, IranDoc and IranMedex databases from 1975 to Aug 2017. Data underwent meta-analysis (random effect model) in CMA2 software. Pooled odds ratios with 95% confidence intervals were calculated for each study. The heterogeneity of the articles was measured using the I² index.

Results

Twenty two articles met the inclusion criteria for 3939 cases and 6077 controls. The pooled OR of “HLA-B27” in BD patients compared with controls was [1.55 (CI 95% 1.01–2.38), P = 0.04]. The OR differ among different countries or geographical areas, focus on domination the European countries. Quality of studies was moderate and heterogeneity was relatively high (I² = 66.9%).

Conclusions

There is a significant correlation between HLA-B27 and Behcet’s Disease, but it was weak. Environmental and genetic factors might determine which the “HLA-B27” alleles manifest Behcet’s disease progression. Future researches is required to perform about what factors can do to positively and separately influence Behcet’s disease.

The genomic landscape of human immune-mediated diseases

As the methodology of genetic detection has developed rapidly in recent years, through techniques such as genome-wide association studies (GWAS) and the secondary generation of sequencing, we are able to view the genomic landscape more clearly. It is well known that genes have a vital role in the pathogenesis of immune-mediated diseases (IMDs), which could provide important insight into new clinical therapeutic targets. Here, we review the genomic landscape of IMDs and analyse overlapping loci between diseases. There may be a need for more epigenetics studies to aid in the understanding of the transition from genotype to phenotype.

Major histocompatibility complex associations of ankylosing spondylitis are complex and involve further epistasis with ERAP1

Ankylosing spondylitis (AS) is a common, highly heritable, inflammatory arthritis for which HLA-B*27 is the major genetic risk factor, although its role in the aetiology of AS remains elusive. To better understand the genetic basis of the MHC susceptibility loci, we genotyped 7,264 MHC SNPs in 22,647 AS cases and controls of European descent. We impute SNPs, classical HLA alleles and amino-acid residues within HLA proteins, and tested these for association to AS status. Here we show that in addition to effects due to HLA-B*27 alleles, several other HLA-B alleles also affect susceptibility. After controlling for the associated haplotypes in HLA-B, we observe independent associations with variants in the HLA-A, HLA-DPB1 and HLA-DRB1 loci. We also demonstrate that the ERAP1 SNP rs30187 association is not restricted only to carriers of HLA-B*27 but also found in HLA-B*40:01 carriers independently of HLA-B*27 genotype.

Ankylosing spondylitis is a common, highly inheritable inflammatory arthritis with poorly understood biology. Here Brown, Cortes and colleagues use fine mapping of the major histocompatibility complex and identify novel associations, and identify other HLA alleles that like HLA-B27 interact with ERAP1 variants to influence disease risk.

Genetic insights into common pathways and complex relationships among immune-mediated diseases

Shared aetiopathogenic factors among immune-mediated diseases have long been suggested by their co-familiality and co-occurrence, and molecular support has been provided by analysis of human leukocyte antigen (HLA) haplotypes and genome-wide association studies. The interrelationships can now be better appreciated following the genotyping of large immune disease sample sets on a shared SNP array: the 'Immunochip'. Here, we systematically analyse loci shared among major immune-mediated diseases. This reveals that several diseases share multiple susceptibility loci, but there are many nuances. The most associated variant at a given locus frequently differs and, even when shared, the same allele often has opposite associations. Interestingly, risk alleles conferring the largest effect sizes are usually disease-specific. These factors help to explain why early evidence of extensive 'sharing' is not always reflected in epidemiological overlap.

HLA-B51/B5 and the risk of Behçet's disease: a systematic review and meta-analysis of case-control genetic association studies

OBJECTIVE

To quantify by meta-analysis the genetic effect of the HLA-B5 or HLA-B51 (HLA-B51/B5) allele on the risk of developing Behçet's disease (BD) and to look for potential effect modifiers.

METHODS

Relevant studies were identified using the PubMed Medline database and manual searches of the literature. Pooled odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated by using the random-effects model. Subgroup meta-analyses and meta-regression analyses were undertaken to investigate the effects of selected study-level parameters on the pooled OR. Heterogeneity was assessed using the I2 statistic. Pooled results were used to calculate population-attributable risks (PAR) for BD in relationship to HLA-B51/B5.

RESULTS

A total of 4,800 patients with BD and 16,289 controls from 78 independent studies (published 1975-2007) were selected. The pooled OR of HLA-B51/B5 allele carriers to develop BD compared with noncarriers was 5.78 (95% CI 5.00-6.67), with moderate between-study heterogeneity (I2 = 61%). The subgroup analyses stratifying studies by geographic locations (Eastern Asia, Middle East/North Africa, Southern Europe, Northern/Eastern Europe) yielded consistent OR ranges (5.31-7.20), with I2 ranges of 52-70%. Univariate random-effects meta-regression indicated the percentage of male BD cases (P = 0.008) as a source of heterogeneity. The PAR within the various geographic areas were estimated at 32-52%.

CONCLUSION

The strength of the association between BD and HLA-B51/B5, and its consistency across populations of various ethnicities, lends further support to this allele being a primary and causal risk determinant for BD. Variations according to sex support an interaction of this allele with BD characteristics.

HLA antigens in a family with Behçet's syndrome

A family is described in which 3 of 12 members suffered from Behçet's syndrome. Four members, including the three patients with Behçet's syndrome suffered from recurrent aphthous stomatitis. These four family members possessed the HLA-haplotype HLA A2, B15, Cw3, DR4. However, one relative had inherited the same HLA-haplotype without showing any symptoms of the disease. Genetic influence from the actual HLA-haplotype may interact in manifestation of the syndrome.

The correlation of MHC haplotype and development of Behçet's disease-like symptoms induced by herpes simplex virus in several inbred mouse strains

It has been postulated that human leukocyte antigen (HLA)-B51 is associated with Behçet's disease. In previous study, we induced Behçet's disease-like symptoms in ICR mice inoculated with herpes simplex virus. In this study, several inbred mouse strains -- B10.BR (H-2k), B10.RIII (H-2r), C57BL/6 (H-2b), C3H/He (H-2k), Balb/c (H-2d) -- which had different types of major histocompatibility complex (MHC), were inoculated with herpes simplex virus type 1 (KOS strain) in order to demonstrate the role of histocompatibility antigen in the development of Behçet's disease-like symptoms. Behçet's disease-like symptoms developed in 40-50% of B10.BR, B10.RIII and C57BL/6 strains, but in only 2% of C3H/He and Balb/c. B10.BR and C3H/He strains had a common haplotype (H-2k) but the rate of manifestation was different. So, we conclude that MHC is not directly correlated with development of Behçet's disease-like symptoms in the animal model of herpes simplex virus induced Behçet's disease-like symptoms.

Vitreoretinal surgery in Behçet's disease with severe ocular complications

PURPOSE

To investigate effects of vitreoretinal surgery in Behçet's disease.

MATERIALS AND METHOD

Vitreoretinal surgery was applied to 26 eyes of 21 patients with Behçet's disease. Preoperative and postoperative visual acuities, number and duration of attacks, anterior and posterior segment pathologies were evaluated.

RESULTS

The mean age of the patients was 33 years and female/male ratio was 6/15. The mean follow-up was 23 months. Visual acuity increased in 15 eyes (58%), did not change in 11 eyes (42%). In the postoperative period, there was a significant decrease in mean number of uveitis attacks compared to the preoperative period (p=0.001), as well as a significant decrease in the mean duration of uveitis attacks (p=0.001). In the postoperative follow-up, intravitreal haemorrhage in 2 eyes (8%), posterior subcapsular cataract in 5 eyes (19%) and corticonuclear cataract in 2 eyes (8%) were observed. Posterior capsular opacification (PCO) developed in 5 of 16 eyes (31%) having ECLE-IOL. CME continued in 3 eyes (12%).

CONCLUSION

Vitreoretinal surgery has favourable effect on the visual and anatomic prognosis in Behçet's patients with severe ocular complications.

A descriptive study on Behçet's disease

This study was performed in order to evaluate the age, sex, geographical distribution, ocular involvement, age of onset, and attacks in Behçet's disease. We examined 540 Behçet patients between 1973-1993. Of the patients, 453 were male and 87 female (m/f: 5.2/1). The average age was 30.7 +/- 0.35. The disease mostly appeared in the third decade and it was statistically significant that sex affected the age at onset of the initial symptoms. The onset of symptoms was more frequent among males in the 25-29-year age group, and among females below 19 and above 35 years of age. The duration of the disease was 28.7 +/- 3.1 months. The state of ocular attacks were evaluated in 598 eyes of 303 patients who were followed regularly during the first year. The risk and frequency of attacks were greater in the eyes with poorer visual acuity, and in such eyes, the number of attacks was greater < or = 24 while smaller > or = 35 years of age.

HLA and Behçet's disease in northern Spain: their lack of correlation with arthritis pattern

We have studied the characteristics of arthritis present in 32 patients with Behçet's disease (BD), and how this arthritis is related to the HLA markers class I. 84% of the patients presented arthritis, the most common being mono-arthritis as the initial presentation, and oligoarthritis in subsequent episodes. In 63% of the cases, the development was in episodes of acute/subacute arthritis. We found statistically significant association between antigens B-5 and B-51, and the group with BD, with a relative risk of 3.89 and 4.71 respectively. The attempt to relate markers B-5, B-51 and B-27 to the presence of arthritis as well as to its manifestation and further development was not conclusive.

Profiling human leukocyte antigens in Vogt-Koyanagi-Harada syndrome

Human leukocyte antigen typing was performed in 32 consecutive Chinese patients with Vogt-Koyanagi-Harada syndrome and 52 unrelated healthy Chinese individuals. Results indicated that HLA-DR4 was identified in 24 of the 32 patients with Vogt-Koyanagi-Harada syndrome (75.0%), but only in 12 (23.1%) of the 52 control subjects (P = .0003; relative risk, 10.0). Human leukocyte antigen-DQw7, also correlated with the disease, was identified in 19 (59.4%) patients, and in 19 control subjects (36.5%; P = .0230). The two-haplotype association detection demonstrated that HLA-DR4 and HLA-DQw7 were related through linkage disequilibrium, suggesting that the disease was primarily associated with only one of the antigens. The comparison between HLA-DR4-positive and HLA-DR4-negative patients with Vogt-Koyanagi-Harada syndrome in regard to clinical manifestations has shown that the HLA-DR4-positive group had a lower visual acuity at the first visit than did the HLA-DR4-negative group. However, both groups responded well to corticosteroid treatment. No other significant correlations between HLA-DR4 positivity and ocular features, including complications or systemic features, were found. Therefore, we concluded that the presence of HLA-DR4 may represent susceptibility to Vogt-Koyanagi-Harada syndrome, but may not represent specific tissue involvement or determine the prognosis. A decreased frequency of HLA-DQw1 in the patient group was also noticed. Further studies showed a higher percentage of HLA-DQw1 in HLA-DR4-positive control subjects than in the HLA-DR4-positive patients (P = .0308), which indicated that HLA-DQw1 was negatively associated with the disease. This protective effect from HLA-DQw1 was also studied.

Behçet's disease in Kuwait, Arabia. A report of 29 cases and a review

Twenty-nine patients with Behçet's disease were studied. Of these, 17 patients were followed up for a mean duration of 37 months and 12 for a mean of 18 months. Male to female ratio was 3.1:1. Of the 29 patients, 26 were Arab, 2 Asian and 1 Black African. The prevalence in the country was 2.1:100,000 population, in Kuwaitis 1.58:100,000, in non-Kuwaiti Arabs, 2.9:100,000 and in non-Arabs, 1.35:100,000 population. The frequencies of the various manifestations were: oral ulcers, 100%; genital ulcers, 93%; skin manifestations, 76%; arthropathy and ocular disease, 69% each; psychiatric disorders, 38%; vascular complications and positive Pathergy test, 34% each; gastrointestinal symptoms, 21%; oesophageal and CNS involvement, 14% each; and peritonism, renal and pulmonary involvement, 7% each. Kuwaiti bedouins seemed to be resistant to the disease, probably due to environmental and/or dietary factors. The hot arid climate of the Gulf had no effect on the course of the disease once it had developed.

[Parameters of hemostasis in Behçet's disease]

Venous thrombosis occurred frequently in Behçet's disease. In 12 patients with Behçet's disease of whom 6 have had leg venous thrombosis, some parameters of hemostasis or fibrinolysis have been studied. Platelet count, fibrinogen level, factor VIII coagulant activity, factor VIII antigen, plasminogen and antithrombin III level were in the normal range. Fibrinolytic capacity in response to venous occlusion of the arms was the same in patients and in healthy subjects, in the patients, there was no difference in regard to the occurrence of venous thrombosis. These parameters seemed therefore not able to detect the thrombotic tendency in this disease. These results are discussed with the other reports of the literature.

Behçet's disease

Behçet's disease is characterized by three primary components: iridocyclitis (historically with hypopyon), aphthous lesions in the mouth, and ulceration of the genitalia. Erythema nodosum, arthropathy and thrombophlebitis often accompany these manifestations, but the ocular symptoms may be the most important and serious manifestations of the disease. Central nervous system involvement, most often due to necrotizing vasculitis, may be the most protean manifestation of the disease, leading to death. The frequency of ocular manifestations is 70-85% in patients with the disease; the underlying disease mechanism in all organ systems is an occlusive vasculitis. Although the most common ocular symptom is that of anterior uveitis, often with hypopyon as a very late sign, the presence of necrotizing retinal vascular lesions is well known and often obscured by the severity of the anterior reaction. Definitions, incidence, clinical characteristics, differential diagnosis, and management of Behçet's ocular disease are discussed, as are the interrelationships of the different organ manifestations. The ophthalmologist should be familiar with the full spectrum of disease presentation since he or she may be the first physician to encounter the Behçet's patient.

A genetic study of Behçet disease in Israel

The frequency of HLA-B5 in 24 Israeli Behçet disease (BD) patients from various subpopulations was significantly greater than in 615 control individuals (P less than 0.003). The relative risk for a B5 carrier to develop BD was calculated to be 5.0. Six patients were offspring of consanguineous marriages, which is not unexpected in the populations studied. Five of the patients had only one HLA-B antigen, which in four cases was B5. Two of the latter were B5 homozygotes, indicating a possible greater susceptibility. This study confirms the reported association between BD and HLA-B5 in a populationnot previously investigated. Furthermore, these data support the suggestion that B5 is associated with BD in populations deriving from the Mediterranean Basin, the Middle East and Far East.