Behcet syndrome (BS) is a multisystemic perivasculitis whose genetic susceptibility is linked to HLA region. We first meta-analysed all HLA class I and II genes involved in BS susceptibility in all ethnic groups worldwide. We identified 1141 articles and finally included 31 case-control studies after multiple rounds of selection. We analysed frequencies for 24 HLA-A alleles (3 alleles for HLA-A∗26 at four digits), 50 HLA-B alleles (11 alleles for HLA-B∗51 at four digits), 15 HLA-C alleles, 16 HLA-DRB1 alleles, 6 HLA-DQB1 alleles, and 15 HLA-DPB1 alleles. We meta-analysed only HLA allelic frequencies from at least three studies; therefore, we investigated 21 alleles out of 140. Going from 7.00 to 1.6 OR, we found 11 class I alleles conferring risk for BS: B∗51:08, B∗51, B∗51:01, B∗51:02, DQB1∗03, A∗26:01, Cw∗14, Cw∗15, Cw∗16, B∗15, and A∗26. Overall, the studies included populations from Europe (Greece, Spain, Italy, Germany, and Ireland), Asia (Korea, China, China Han, and Thailand), Middle East (Israel, Saudi Arabia, and Iran), and Morocco (as no other North-African population was included). We collected a number of ethnical groups sufficient to conduct an ethnic-specific meta-analysis where Europeans showed 11.25 OR for B∗51:08 and Japan 3.50 OR for A∗26:01. A remarkable result was that the most frequent HLA−B∗51 two-digit alleles associated with BS were different among populations: HLA−B∗51:08 in Europe, HLA−B∗51:01 in Turkey, and HLA−B∗51:02 in Japan. Overall, we discussed our real-world results with other imputation studies.

Multiple Sclerosis (MS) displays a heterogeneous clinical onset and progression, which are mostly unpredictable, but demyelination of the central nervous system (CNS) leads to substantial deficits of sensory, motor, autonomic, and neurocognitive functions. Considering all genetic studies on MS, including the advanced genome-wide association studies, the risk linked to HLA alleles remains the highest among other susceptibility genetic variants. However, given the genetic variability of HLA alleles in different ethnic groups, we conducted a systematic review of reviews and meta-analyses aiming at summarizing all the results on the association between MS and HLA class II genes. We systematically searched meta-analyses and systematic reviews dealing with MS and HLA in all ethnicities. From 154 records, we included 5 articles collecting HLA data from 15,232 MS patients and 24,194 ethnically matched controls. DRB1∗15 (OR ranging from 1.39 in Chinese Han to 2.59 in Caucasians) and DQB1∗06:02 (OR ranging from 1.91 in Caucasians to 2.49 in Colombian) alleles confer an increased risk for MS transethnically (Caucasians, Chinese, South Americans, Carribeans, Middle Easterners, Japanese, and North Africans). DRB1∗01, DRB1∗09, DRB1∗11, DRB1∗12, and DRB1∗16 alleles were protective, in agreement with the type of amino-acidic (aa) residues (ranging from position 9 to 90) included in pockets 1, 4, 6, 7, and 9, which are most involved in peptide presentation. Changes in aa residues affect the capability of HLA molecules in binding myelin peptides. DQB1∗06:02 risk allele seems to be the most interesting target as humanized mice expressing only DQB1∗06:02 develop MS-like disease mediated by autoimmune reactions against myelin oligodendrocytic basic protein that stabilizes the myelin. Our summary of results from a high number of patients and controls suggests that allelic variants from both DQB1 and DRB1 genes are equally involved in MS susceptibility/protection transethnically.

HLA typing requests for association studies of immune-mediated diseases are often redundant and inadequate. We designed a series of meta-analyses to evaluate the accuracy of typing and distribution of HLA alleles predisposing to diseases, aiming at developing an app that can help doctors in choosing the most suitable molecular analysis. The first study was on celiac disease (CD) and HLA-DQ in children. We searched all english articles published in the main bibliographic databases up to May 2016. The search strategy has been developed using controlled terms (e.g. MeSH) and free terms. We identified 1885 articles. 1334 abstracts were examined. 46 manuscripts were evaluated, and 13 studies were included in the meta-analysis (740 CD and 943 controls). The risk of developing CD in children with allelic variants encoding the HLA-DQ2.5 and/or HLA-DQ8 molecules has been confirmed. The greatest CD risk resides in carriers of two DQ2.5 molecules, i.e. subjects homozygous for the DQB1*02:01 and DQA1*05 alleles (OR=5.4, 95 % CI=4.1-6.8) compared to any other DQ genotype. Carriers of two DQB1*02:01 (chain β2) alleles and one DQA1*05 (chain α5) allele have the same risk (p=0.8089) of DQ2.5 homozygotes (OR=5.3%, 95 CI=4,1 to 6.5). We found no differences between DQ8/β2 and DQ2.5/DQ8, nor between β2/DQX and DQ2.5/X. We suggest a two-step process: first typing the DQB1*02:01 allele and, in case of a negative result, full typing of HLA-DQ.

Specific HLA-DQ genes have been recognized as necessary - but not sufficient - factors for the occurrence of Celiac Disease (CD). Through a meta-analysis, evaluating the distribution of CD-related HLA genotypes in children, we aimed at providing insights for a potential widened screening strategy. After a systematic search on the association between class II HLA genes and CD in children, 46 publications were obtained and assessed for eligibility. A total of 13 eligible studies were submitted to data extraction and analysis (10 case–control studies and 3 cohort studies). Case–control studies collectively enrolled 740 CD patients and 943 controls. In the population-stratified analysis, the following alleles conferred a significantly increased risk for CD: HLA-DQB1*02 (odds ratio [OR]=10.28) and HLA-DQB1*03:02 (OR=2.24). By drafting a risk gradient to develop CD according to HLA genetic background, the highest risk is confirmed to exist for DQ2/DQ2 homozygous subjects, regardless of the ethnicities (OR=5.4). Actually, the genotype DQ2/β2 showed basically the same risk (OR=5.3). Indeed, no differences have been found in CD risk between DQ2/β2 and DQ2/DQ2, as well as between DQ8/β2 and DQ2/DQ8, and between β2/DQX and DQ2/X. The HLA-DQB1*02:01 allele is present in more than 90% CD children. In the perspective of a widened pediatric population screening for CD, a double-step process might be suggested: HLA-DQB1*02:01 might be investigated first and, only if this result is positive, children might be candidate for a prospective serologic screening, as a second step.

The competitive binding between CpG-ODN (single-stranded DNA from pathogens) and HLA-B and HLA-A ligands for the inhibitory Killer Immunoglobulin-like Receptors (KIR)3DL1/2 may lead to possible hypo-sensing of pathogens and ineffective clearance. We observed an overabundance of HLA ligands for inhibitory KIR with three domains in KD subjects.

we performed a meta-analysis to assess the usefulness of HLA testing for Narcolepsy diagnosis in four major ethnical groups: Asians, Afro-Americans, Amerindians and Caucasians.PubMed, EMBASE, Web of Science, Scopus and Cochrane databases were searched for articles in English and French published before October 2017 on HLA class II alleles in Narcolepsy. We included case-control studies, cross-sectional and retrospective cohort studies with patients diagnosed following the International classifications of sleep disorders (1990-2012) and ethnically matched controls. Following PRISMA guidelines, two investigators independently extracted data according to the inclusion criteria listed in PROSPERO CRD42017058677. A third researcher was consulted for discrepancies. We extracted and pooled adjusted OR using random-effect models. We verified the strength of the association between HLA-DQB1*06:02 and the worldwide distribution of Narcolepsy type 1 (NT1) and type 2 (NT2); furthermore, we pooled the OR measuring the association between HLA-DQB1*06:02 and NT1, NT2 and hypersomniacs.We identified 511 titles. Of these, 12 case-control studies were included, for a total of 2077 NT1 patients, 235 NT2 patients, 161 hypersomniacs and 7802 controls. In the population-stratified analysis, HLA-DQB1*06:02 conferred an increased risk for NT1 (OR: 24.1, IC: 14.6-39.5, p < 0.001) and NT2 (OR: 3.9; IC: 2.2-6.8, p < 0.001). For NT1 the pooled estimated positive Likelihood Ratio (LR+) was 5.94 (IC: 3.71-9.51) and the negative Likelihood Ratio (LR-) was 0.23 (IC: 0.16-0.33); for NT2 LR+ was 3.35 (IC: 2.08-5.38) and LR- 0.72 (IC: 0.63-0.81). Moreover, for hypersomniacs LR+ was 1.436 (IC 0.668-3.089) and LR- 0.903 (IC 0.714-1.142).Our data support the preponderant role of HLA-DQB1*06:02 in susceptibility to NT1/NT2 across all ethnicities. HLA-DQB1*06:02 negativity should make clinicians cautious in excluding other diagnoses.

HLA typing requests for association studies of immune-mediated diseases are often redundant and inadequate. We designed a series of meta-analyses to evaluate the accuracy of typing and distribution of HLA alleles predisposing to diseases, aiming at developing an app that can help doctors in choosing the most suitable molecular analysis. The first study was on celiac disease (CD) and HLA-DQ in children. We searched all english articles published in the main bibliographic databases up to May 2016. The search strategy has been developed using controlled terms (e.g. MeSH) and free terms. We identified 1885 articles. 1334 abstracts were examined. 46 manuscripts were evaluated, and 13 studies were included in the meta-analysis (740 CD and 943 controls). The risk of developing CD in children with allelic variants encoding the HLA-DQ2.5 and/or HLA-DQ8 molecules has been confirmed. The greatest CD risk resides in carriers of two DQ2.5 molecules, i.e. subjects homozygous for the DQB1*02:01 and DQA1*05 alleles (OR=5.4, 95 % CI=4.1-6.8) compared to any other DQ genotype. Carriers of two DQB1*02:01 (chain β2) alleles and one DQA1*05 (chain α5) allele have the same risk (p=0.8089) of DQ2.5 homozygotes (OR=5.3%, 95 CI=4,1 to 6.5). We found no differences between DQ8/β2 and DQ2.5/DQ8, nor between β2/DQX and DQ2.5/X. We suggest a two-step process: first typing the DQB1*02:01 allele and, in case of a negative result, full typing of HLA-DQ.

Juvenile Idiopathic Arthritis (JIA) is characterized with a variable pattern of articular involvement and systemic symptoms and, thus, it has been classified in several subtypes. Genetic predisposition to JIA is mainly due to HLA class II molecules (HLA-DRB1, HLA-DPB1), although HLA class I molecules and non-HLA genes have been implicated, too. Here, we carried out a meta-analysis including selected studies designed to assess HLA genetic background of JIA patients, compared to healthy controls; particularly, we focused our attention on HLA-DRB1. In summary, our meta-analysis showed four main findings regarding HLA-DRB1 locus as a genetic factor of JIA: i) HLA-DRB1*08 is a strong factor predisposing to JIA, both for oligo-articular and poly-articular forms (oJIA>pJIA); ii) HLA-DRB1*01 and HLA-DRB1*04 may be involved in the genetic predisposition of Rheumatoid Factor (RF) positive forms of JIA; iii) HLA-DRB1*11 was confirmed to be predisposing to oligo-articular JIA; iv) HLA-DRB1*04 was confirmed to have a role in systemic JIA. Importantly, RF positivity seems to select the JIA clinical subset with the strongest immunogenetic similarities with adult rheumatoid arthritis.

Context: Little is known about soluble HLA-G (sHLA-G) concentrations in obese pregnant women with uncomplicated pregnancies.Objective: To investigate the role of sHLA-G in obese pregnancies.Design: Case-control study, from 2013 to 2015.Setting: A tertiary care centre.Patients: 168 healthy normal weight women and 59 overweight/obese women; to avoid the effect of preeclampsia on sHLA-G concentrations, cases were further divided in two groups: 42 with normotensive pregnancy and 17 who developed preeclampsia.Interventions: all the women enrolled received standard antenatal care and plasma sample collections were performed.Main outcome measures: 5HLA-G concentrations during pregnancy, before delivery and in cord blood.Results: Maternal sHLA-G concentrations in overweight/obese with normotensive pregnancies increased by 14.7% (IQR= 26.4 to +89.6) in the 2nd trimester and by 19.6% (IQR=-33 to +104) before delivery and were significantly higher than in controls (p = 0.024). Median cord blood sHLA-G concentrations were 53.5 ng/ml (IQR= 36-62.7) in the overweight/obese women with uncomplicated pregnancies (p <0.001 compared to controls) and 19.7 ng/ml (IQR = 7.5-36.3) in controls. Maternal concentrations of sHLAG in the two trimesters and before delivery were significantly lower among subjects who developed preeclampsia than in controls (p < 0.001) or in obese subjects with normotensive pregnancies (p < 0.001).Conclusions: sHLA-G concentratons are higher in normotensive overweight/obese women and their babies while lower in preeclamptic overweight/obese women and their cords. Obesity influences maternal and fetal sHLA-G concentrations during pregnancy, to optimize the reproductive success, while preeclampsia impairs the mother-offspring antinflammatory response. (C) 2016 Elsevier Ireland Ltd. All rights reserved.

We enrolled 151 healthy mother/newborn couples and 26 with gestational diabetes mellitus (GDM). HLA-G and PAPP-A plasma levels were measured by ELISA at first and second trimesters, at delivery, and in cord blood. HLA-G 14 bp ins/del and PAPP-A A/C polymorphisms were genotyped. HLA-G del/del and PAPP-A C/C genotypes were more frequent among GDM mothers than controls. We observed a genetic epistasis between the two polymorphisms: the HLA-G del/del and PAPP-A C/C combination was carried by 8% of GDM mothers and 1.3% of controls (OR = 9.5, 95% CI = 0.8-109, p = 0 07). GDM mothers showed increased sHLA-G levels compared to controls (p = 0 004), and those carrying the HLA-G del/del genotype produced more sHLA-G at the second trimester and at delivery (p = 0 014). A genetic pressure by fetal genotype on maternal sHLA-G production was observed in GDM mothers with heterozygous HLA-G del/ins newborns (p = 0 02). Babies born to GDM mothers showed higher sHLA-G concentrations compared to those born to healthy mothers, and those carrying HLA-G del/del showed the highest sHLA-G levels (p = 0 013). PAPP-A amounts significantly increased along pregnancy (p < 0 001), but the median levels at the first and second trimesters were significantly lower in GDM (p = 0 03). Our findings first suggest an involvement of HLA-G and PAPP-A gene-protein interaction in GDM and highlight a possible contribution of the fetus in balancing maternal inflammation.

Patients with cystic echinococcosis (CE) can harbour cysts for years or even decades, apparently without effect of the immune system on the metacestode. Although several immune evasion mechanisms by echinococcal cysts have been described, it is unclear whether the human leucocyte antigen (HLA) system plays a role in the susceptibility or resistance to CE in humans. HLA-G molecules are known to exert a suppressive action on dendritic cells maturation and on natural killer (NK) cells functions, therefore hampering T-cell responses and NK cytolysis. HLA-G plays an important role in immune tolerance, is involved in foetus and in allotransplant tolerance, and may be involved in tumoral and viral immune evasion. In this study, we assessed the presence and levels of soluble HLA-G (sHLA-G) in patients with CE using a commercial ELISA kit to determine whether host's HLA-G may have a role in the course of human CE.

Objective: To evaluate soluble HLA-G (sHLA-G) concentrations in maternal blood serum and cervical vaginal fluid in pregnancies complicated by preterm premature rupture of membranes (PPROM) compared to controls.Study design: Case-control study of 24 women with PPROM and 40 controls.Main outcome measures: Vaginal and serum sHLA-G and IL-6 concentrations.Findings: Women with PPROM had significantly higher serum and vaginal sHLA-G concentrations compared to controls (respectively median 31.48 U\ml versus 13.9 U\ml p < 0.001 and 1.7 U\ml versus 0.1 U\ml p <0.001). Vaginal expression of IL-6 was higher in PPROM cases compared to controls (respectively, median 31.19 pg\ml versus 6.67 pg\ml; p <0.001). Higher serum and vaginal sHLA-G were associated with both a shorter length of pregnancy and histological chorioamnionitis in the PPROM group.Conclusions: Higher vaginal and serum sHLA-G in PPROM cases may be a sign of local and systemic inflammation. (C) 2016 Elsevier Ireland Ltd. All rights reserved.