Dataset Information

Interaction between HLA-DRB1-DQB1 haplotypes in Sardinian multiple sclerosis population.

ABSTRACT: We performed a case-control study in 2,555 multiple sclerosis (MS) Sardinian patients and 1,365 healthy ethnically matched controls, analyzing the interactions between HLA-DRB1-DQB1 haplotypes and defining a rank of genotypes conferring a variable degree of risk to the disease. Four haplotypes were found to confer susceptibility (*13:03-*03:01 OR = 3.3, Pc 5.1 × 10(-5), *04:05-*03:01 OR = 2.1, Pc 9.7 × 10(-8), *15:01-*06:02 OR = 2.0, Pc = 9.1 × 10(-3), *03:01-*02:01 OR = 1.7 Pc = 7.9 × 10(-22)) and protection (*11, OR = 0.8, Pc = 2.7 × 10(-2), *16:01-*05:02 OR = 0.6, Pc = 4.8 × 10(-16), *14:01-4-*05:031 = OR = 0.5, Pc = 9.8 × 10(-4) and *15:02-*06:01 OR = 0.4, Pc = 5.1 × 10(-4)). The relative predispositional effect method confirms all the positively associated haplotypes and showed that also *08 and *04 haplotypes confers susceptibility, while the *11 was excluded as protective haplotype. Genotypic ORs highlighted two typologies of interaction between haplotypes: i) a neutral interaction, in which the global risk is coherent with the sum of the single haplotype risks; ii) a negative interaction, in which the genotypic OR observed is lower than the sum of the OR of the two haplotypes. The phylogenic tree of the MS-associated DRB1 alleles found in Sardinian patients revealed a cluster represented by *14:01, *04:05, *13?03, *08:01 and *03:01 alleles. Sequence alignment analysis showed that amino acids near pocket P4 and pocket P9 differentiated protective from predisposing alleles under investigation. Furthermore, molecular dynamics simulation performed on alleles revealed that position 70 is crucial in binding of MBP 85-99 peptide. All together, these data suggest that propensity to MS observed in Sardinian population carried by the various HLA-DRB1-DQB1 molecules can be due to functional peculiarity in the antigen presentation mechanisms.

SUBMITTER: Cocco E

PROVIDER: S-EPMC3620236 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature

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Interaction between HLA-DRB1-DQB1 haplotypes in Sardinian multiple sclerosis population.

Cocco Eleonora E Murru Raffaele R Costa Gianna G Kumar Amit A Pieroni Enrico E Melis Cristina C Barberini Luigi L Sardu Claudia C Lorefice Lorena L Fenu Giuseppe G Frau Jessica J Coghe Giancarlo G Carboni Nicola N Marrosu Maria Giovanna MG

PloS one 20130408 4

We performed a case-control study in 2,555 multiple sclerosis (MS) Sardinian patients and 1,365 healthy ethnically matched controls, analyzing the interactions between HLA-DRB1-DQB1 haplotypes and defining a rank of genotypes conferring a variable degree of risk to the disease. Four haplotypes were found to confer susceptibility (*13:03-*03:01 OR = 3.3, Pc 5.1 × 10(-5), *04:05-*03:01 OR = 2.1, Pc 9.7 × 10(-8), *15:01-*06:02 OR = 2.0, Pc = 9.1 × 10(-3), *03:01-*02:01 OR = 1.7 Pc = 7.9 × 10(-22)) ...[more]

PMID: 23593151

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Project description:INTRODUCTION: Genetic predisposition to multiple sclerosis (MS) in Sardinia (Italy) has been associated with five DRB1*-DQB1* haplotypes of the human leukocyte antigen (HLA). Given the complexity of these associations, an in-depth re-analysis was performed with the specific aims of confirming the haplotype associations; establishing the independence of the associated haplotypes; and assessing patients' genotypic risk of developing MS. METHODS AND RESULTS: A transmission disequilibrium test (TDT) of the DRB1*-DQB1* haplotypes in 943 trio families, confirmed a higher than expected transmission rate (over-transmission) of the *13:03-*03:01 (OR = 2.9, P = 7.6×10(-3)), *04:05-*03:01 (OR = 2.4, P = 4.4×10(-6)) and *03:01-*02:01 (OR = 2.1, P = 1.0×10(-15)) haplotype. In contrast, the *16:01-*05:02 (OR = 0.5, P = 5.4×10(-11)) and the *15:02-*06:01 (OR = 0.3, P = 1.5×10(-3)) haplotypes exhibited a lower than expected transmission rate (under-transmission). The independence of the transmission of each positively and negatively associated haplotype was confirmed relative to all positively associated haplotypes, and to the negatively associated *16:01-*05:02 haplotype. In patients, carriage of two predisposing haplotypes, or of protective haplotypes, respectively increased or decreased the patient's risk of developing MS. The risk of MS followed a multiplicative model of genotypes, which was, in order of decreasing ORs: *04:05-*0301/*03:01-*02:01 (OR = 4.5); *03:01-*02:01/*03:01-*02:01 (OR = 4.1); and the *16:01-*05:02/*16:01-*0502 (OR = 0.2) genotypes. Analysis of DRB1 and DQB1 protein chain residues showed that the Val/Gly residue at position 86 of the DRB1 chain was the only difference between the protective *16:01- *15:02 alleles and the predisposing *15:01 one. Similarly, the Ala/Val residue at position 38 of the DQB1 chain differentiated the positively associated *06:02 allele and the negatively associated *05:02, *06:01 alleles. CONCLUSIONS: These findings show that the association of specific, independent DRB1*-DQB1* haplotypes confers susceptibility or resistance to MS in the MS-prone Sardinian population. The data also supports a functional role for specific residues of the DRB1 and DQB1 proteins in predisposing patients to MS.

Project description:Multiple sclerosis (MS), a common central nervous system inflammatory disease, has a major heritable component. Susceptibility is associated with the MHC class II region, especially HLA-DRB5*0101-HLA-DRB1*1501-HLA-DQA1*0102-HLA-DQB1*0602 haplotypes(hereafter DR2), which dominate genetic contribution to MS risk. Marked linkage disequilibrium (LD) among these loci makes identification of a specific locus difficult. The once-leading candidate, HLA-DRB1*15, localizes to risk, neutral, and protective haplotypes. HLA-DRB1*15 and HLA-DQB1*0602, nearly always located together on a small ancestral chromosome segment, are strongly MS-associated. One intervening allele on this haplotype, viz. HLA-DQA1*0102, shows no primary MS association. Two Canadian cohorts (n = 830 and n = 438 trios) genotyped for HLA-DRB1, HLA-DQA1 and HLA-DQB1 alleles were tested for association using TDT. To evaluate epistasis involving HLA-DRB1*15, transmissions from HLA-DRB1*15-negative parents were stratified by the presence/absence of HLA-DRB1*15 in affected offspring. All 3 alleles contribute to MS susceptibility through novel epistatic interactions. HLA-DQA1*0102 increased disease risk when combined with HLA-DRB1*1501 in trans, thereby unambiguously implicating HLA-DQ in MS susceptibility. Three-locus haplotypes demonstrated that HLA-DRB1*1501 and HLA-DQB1*0602 each influence risk. Transmissions of rare morcellated DR2 haplotypes showed no interaction with HLA-DQA1*0102. Incomplete haplotypes bearing only HLA-DRB1*1501 or HLA-DQB1*0602 did not predispose to MS. Balanced reciprocal transmission distortion can mask epistatic allelic association. These findings implicate epistasis among HLA class II alleles in human immune responses generally, provide partial explanation for intense linkage disequilibrium in the MHC, have relevance to animal models, and demonstrate key roles for DR2-specific interactions in MS susceptibility. MHC disease associations may be more generally haplotypic or diplotypic.

Project description:ObjectiveSystemic sclerosis (SSc) is a rare disease that is particularly uncommon in children. Specific HLA alleles have been associated with SSc in adults. This study was undertaken to investigate HLA class II alleles in juvenile-onset SSc.MethodsDRB1, DQA1, and DQB1 alleles were determined by DNA-based HLA typing. Analyses were conducted comparing Caucasian patients with juvenile-onset SSc (n = 76) to healthy Caucasian controls (n = 581).ResultsInitial analyses focused on HLA class II associations previously reported in adult Caucasian patients with SSc. The frequency of DRB1*11 was not significantly increased in juvenile-onset SSc (22.4% of patients with juvenile-onset SSc versus 17.6% of controls; odds ratio [OR] 1.35, P = 0.34), nor were the specific DRB1*11:01 or *11:04 alleles. DQA1*05, a risk factor previously identified in adult men with SSc, was increased in patients with juvenile-onset SSc versus controls (57.9% versus 44.1%; OR 1.76, P = 0.027), as was DRB1*03 (34.2% versus 22.5%; OR 1.79, P = 0.031). Secondary analyses of all DRB1 allele groups revealed an association with DRB1*10 (10.5% of patients with juvenile-onset SSc versus 1.5% of controls; OR 7.48, P = 0.0002). As this is a new observation, correction was made for multiple comparisons of 13 different DRB1 allele groups; results nevertheless remained significant (P = 0.003). Also, a lower frequency of DRB1*01 was observed in patients with juvenile-onset SSc who were younger at disease onset (OR 0.06, P = 0.01) and in those with antibodies to topoisomerase (OR 0.14, P = 0.024).ConclusionAssociations of HLA alleles with juvenile-onset SSc differed from associations with SSc in women, but were similar to associations with SSc in men. Additionally, a novel association with DRB1*10 was observed in children. The greatest proportion of genetic risk of SSc is contributed by the HLA complex, and the current study reveals the importance of the association of HLA class II genes in juvenile-onset SSc.

Project description:The Major Histocompatibility Complex (MHC, 6p21) codes for traditional HLA and other host response related genes. The polymorphic HLA-DRB1 gene in MHC Class II has been associated with several complex diseases. In this study we focus on MHC haplotype structures in the Finnish population. We explore the variability of extended HLA-DRB1 haplotypes in relation to the other traditional HLA genes and a selected group of MHC class III genes. A total of 150 healthy Finnish individuals were included in the study. Subjects were genotyped for HLA alleles (HLA-A, -B, -DRB1, -DQB1, and -DPB1). The polymorphism of TNF, LTA, C4, BTNL2 and HLA-DRA genes was studied with 74 SNPs (single nucleotide polymorphism). The C4A and C4B gene copy numbers and a 2-bp silencing insertion at exon 29 in C4A gene were analysed with quantitative genomic realtime-PCR. The allele frequencies for each locus were calculated and haplotypes were constructed using both the traditional HLA alleles and SNP blocks. The most frequent Finnish A∼B∼DR -haplotype, uncommon in elsewhere in Europe, was A*03∼B*35∼DRB1*01∶01. The second most common haplotype was a common European ancestral haplotype AH 8.1 (A*01∼B*08∼DRB1*03∶01). Extended haplotypes containing HLA-B, TNF block, C4 and HLA-DPB1 strongly increased the number of HLA-DRB1 haplotypes showing variability in the extended HLA-DRB1 haplotype structures. On the contrary, BTNL2 block and HLA-DQB1 were more conserved showing linkage with the HLA-DRB1 alleles. We show that the use of HLA-DRB1 haplotypes rather than single HLA-DRB1 alleles is advantageous when studying the polymorphisms and LD patters of the MHC region. For disease association studies the HLA-DRB1 haplotypes with various MHC markers allows us to cluster haplotypes with functionally important gene variants such as C4 deficiency and cytokines TNF and LTA, and provides hypotheses for further assessment. Our study corroborates the importance of studying population-specific MHC haplotypes.

Dataset Information

Interaction between HLA-DRB1-DQB1 haplotypes in Sardinian multiple sclerosis population.

Publications

Interaction between HLA-DRB1-DQB1 haplotypes in Sardinian multiple sclerosis population.

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