DQB1 Loci Research Articles

Genetic variability in COVID-19-related genes in the Brazilian population

SARS-CoV-2 utilizes the angiotensin-converting enzyme 2 (ACE2) receptor and transmembrane serine protease (TMPRSS2) to infect human lung cells. Previous studies have suggested that different host ACE2 and TMPRSS2 genetic backgrounds might contribute to differences in the rate of SARS-CoV-2 infection or COVID-19 severity. Recent studies have also shown that variants in 15 genes related to type I interferon immunity to influenza virus might predispose patients toward life-threatening COVID-19 pneumonia. Other genes (SLC6A20, LZTFL1, CCR9, FYCO1, CXCR6, XCR1, IL6, CTSL, ABO, and FURIN) and HLA alleles have also been implicated in the response to infection with SARS-CoV-2. Currently, Brazil has recorded the third-highest number of COVID-19 cases worldwide. We aimed to investigate the genetic variation present in COVID-19-related genes in the Brazilian population. We analyzed 27 candidate genes and HLA alleles in 954 admixed Brazilian exomes. We used the information available in two public databases (http://www.bipmed.org and http://abraom.ib.usp.br/) and additional exomes from individuals born in southeast Brazil, the region of the country with the highest number of COVID-19 patients. Variant allele frequencies were compared with the 1000 Genomes Project phase 3 (1KGP) and gnomAD databases. We detected 395 nonsynonymous variants; of these, 325 were also found in the 1KGP and/or gnomAD. Six of these variants were previously reported to influence the rate of infection or clinical prognosis of COVID-19. The remaining 70 variants were identified exclusively in the Brazilian sample, with a mean allele frequency of 0.0025. In silico analysis revealed that seven of these variants are predicted to affect protein function. Furthermore, we identified HLA alleles previously associated with the COVID-19 response at loci DQB1 and DRB1. Our results showed genetic variability common to other populations and rare and ultrarare variants exclusively found in the Brazilian population. These findings might lead to differences in the rate of infection or response to infection by SARS-CoV-2 and should be further investigated in patients with this disease.

Molecular analysis of HLA Class I and Class II genes in five different South Indian linguistic groups.

South Indians are a heterogeneous population who speak different languages and differ in their life style and physical appearance. Major population movements, social structure and caste endogamy have influenced the genetic structure of Indian populations. The human leukocyte antigen (HLA) system of populations is highly informative because of the high level of polymorphisms. Knowledge of allele and haplotype frequencies of the HLA system is important in the search for unrelated bone marrow donors. We investigated the distribution of HLA A, B, C, DRB1 and DQB1 loci in five linguistic groups from South India. HLA-A*01:01:01~B*57:01:01:01~C*06:02:01~DRB1*07:01:01~DQB1*03:03:02 was the common haplotype with highest frequency in all the five populations studied. A few relevant haplotypes were identified as most common haplotypes in each linguistic group. Comparison of HLA-A, -B and -DRB1 allele distribution in these five linguistic groups with the other Asian population showed that the South Indian populations were closely related to Sri Lankan populations. A large South Indian donor registry might serve as good source of donors for patients from Sri Lanka and vice versa.

Diversities of HLA-A, -B, -C, -DRB1 and -DQB1 loci in Chinese Kazak population and its genetic relatedness dissection with multiple populations: a comparative study

Studying the allele and haplotype distributions of human leukocyte antigen (HLA) loci at 2nd-field level in different populations was important. Allele and haplotype frequencies of HLA-A, -B, -C, -DRB1 and -DQB1 loci in 110 unrelated healthy Kazak individuals living in Xinjiang (China) were analyzed using polymerase chain reaction sequence based typing. Thirty HLA-A, 48 HLA-B, 24 HLA-C, 34 HLA-DRB1 and 18 HLA-DQB1 alleles were detected at the 2nd-field level in the Kazak population. Frequencies of HLA alleles, genotypes, and haplotypes were calculated, and some exhibited significantly different distributions among different populations. A neighbor-joining (NJ) tree, heatmap, multidimensional scaling (MDS) and principal component analysis (PCA) were used to explore the genetic relationships between the Kazak population and 32 reference populations distributed in Asia, Africa, America and Europe using frequency data of HLA-A, -B, -C and -DRB1 loci. The NJ tree, heatmap, and MDS of the 33 populations were constructed based on pairwise DA values of populations obtained by the HLA-A, -B, -C and -DRB1 allele frequencies. Different PCA plots were constructed based on the allele frequencies of HLA-A, -B, -C and -DRB1 or estimated haplotypic frequencies of HLA-A, -B, -C loci. The data obtained in the present research can be used for research on HLA-related diseases or paternity relationships, and aid to finding the best matched donors in stem cell transplantation for Kazak individuals.

High-resolution mapping identifies HLA class II associations with multifocal motor neuropathy

ObjectiveTo gain further insight in the immunopathology underlying multifocal motor neuropathy (MMN) by exploring the association between MMN and the human leukocyte antigen (HLA) class II DRB1, DQB1, and DQA loci in depth and by correlating associated haplotypes to detailed clinical and anti-ganglioside antibody data. MethodsWe performed high-resolution HLA-class II typing for the DRB1, DQB1, and DQA1 loci in 126 well-characterized MMN patients and assessed disease associations with haplotypes. We used a cohort of 1305 random individuals as a reference for haplotype distribution in the Dutch population. ResultsThe DRB1*15:01-DQB1*06:02 haplotype (OR 1.6 [95% CI 1.1–2.2], p < 0.05) and the DRB1*12:01-DQB1*03:01 haplotype (OR 2.7 [95% CI 1.2–5.5], p < 0.05) were more frequent in patients with MMN than in controls. These haplotypes were not associated with disease course, response to treatment or anti-ganglioside antibodies. ConclusionsMMN is associated with the DRB1*15:01-DQB1*06:02 and DRB1*12:01-DQB1*03:01 haplotypes. These HLA molecules or gene variants in their immediate vicinity may promote the specific inflammatory processes underlying MMN.

Evaluation of LabType-SSO HLA Typing for HLA-A, -B, -C, -DRB1, and -DQB1 loci.

For HLA genotyping, PCR sequence-specific oligonucleotide (SSO) methods using the Luminex platform are widely used. We evaluated the performance of LabType-SSO (One Lambda, USA) in Koreans. LabType-SSO were performed on 50 residual DNA samples analyzed by sequence-based typing (SBT) for all HLA-A, -B, -C, -DRB1, and -DQB1 alleles with gene frequency > 0.1% in Koreans. The LabType-SSO results were in complete agreement with SBT at the 2-digit level. For 4-digit level, 9 HLA-A alleles, 1 HLA-B allele, 3 HLA-C alleles, neither HLA-DRB1 nor -DQB1 allele showed ambiguous results for assignment of most probable types considering HLA gene frequency in Koreans. In addition, two cases of DQB1*04:01 allele were incorrectly assigned to DQB1*04:02. LabType-SSO tests showed accurate assignment of 2-digit level and LabType-SSO HLA-DRB1 test showed correct 4-digit most probable HLA type. The tests can be useful as intermediate resolution typing for solid organ transplantation.

Distribution of HLA class Ⅰ and class Ⅱ haplotypes in Chinese Han population based on family segregation

HLA haplotype analysis has important application value in human population genetics, anthropological research and HLA matching transplantation. Based on HLA-A, -B, -C, -DRB1 and -DQB1 genotyping data from 663 families including 663 leukemia patients and 991 related donors, the allele frequency (AF) and haplotype frequency (HF) of two-, three- and five-locus haplotype distribution patterns in the Chinese Han population were determined by family segregation. A total of 38 alleles at A locus, 75 alleles at B locus, 35 alleles at C locus, 53 alleles at DRB1 locus and 22 alleles at DQB1 locus were discovered in this population. The frequencies of these alleles were basically consistent with those of previous reports except for some tiny differences. The study found 11 A-C, 15 C-B, 4 B-DRB1 and 11 DRB1-DQB1 two-locus haplotypes with a frequency over 2%. The number of A-C-B and A-B-DRB1 three-locus haplotype with a frequency over 1% were 11 and 3 respectively. The most common HLA-A-C-B-DRB1-DQB1 haplotype (HF>1%) were A*3001-C*0602-B*1302-DR*0701-DQ*0202 (4.30%), A*0207-C*0102-B*4601-DR*0901-DQ*0303 (3.07%), A*3303-C*0302-B*5801-DR*0301-DQ*0201 (1.49%) and A*1101-C*0102-B*4601-DR*0901-DQ*0303 (1.01%). The results are helpful for finding matching donors for hematopoietic stem cell transplant patients and also contribute to transplant immunology, HLA-related diseases, research of human genetics and other fields.

Immunogenetic aspects of idiopathic recurrent miscarriage in the Kazakh population.

There are numerous scientific studies of recurrent miscarriage (RM) with possible causes, such as fetal chromosomal abnormalities, infectious agents, adverse environmental factors, bad habits, anatomical defects, thrombophilic disorders, etc. However, RM causes in 50% of cases remain unknown. These RM cases do not have any explainable etiology, and they require in-depth etiopathogenesis study, thus they are considered idiopathic RM. The purpose of this research is to study polymorphisms relationship of the immune response genes CX3CR1 (rs3732379, Val249Ile), CTLA4 (rs3087243, CT60 G/A), and HLA DQA1, DQB1, DRB1 (major histocompatibility complex, class II) with the idiopathic form of recurrent miscarriage (iRM) development in Kazakh population. Independent replicative TagMan genotyping for 302 patients with iRM and 300 women with normal reproduction was performed. It has been shown that carriage of unfavorable genotypes (Val/Ile, Val/Val) by the Val249Ile polymorphism of the CX3CR1 gene increases the risk of developing iRM by 1.43 times. Search for associations of genes allelic variants of HLA class 2 complex with iRM revealed *501 allele in DQA1 locus, *0301 in DQB1 locus, *10, *12, *15, *16 alleles in DRB1 locus, which increases the risk of developing iRM in Kazakh population with OR from 1.34 to 4.5. As a result of the study, obtained highly significant associations of immune response genes with the development of iRM in the Kazakh population indicate the possible involvement of the immune system interaction of mother cells with syncytiotrophoblast, which is realized by vascularization defects, defective embryo implantation, and leads to early pregnancies’ termination.

Characterization of 15 novel HLA alleles by next generation sequencing in Brazilian individuals.

Fifteen novel HLA alleles in the HLA-A, -B, -C, DRB1, and DQB1 loci were described.

Impact of HLA Evolutionary Divergence on Clinical Features of Patients with Aplastic Anemia and Paroxysmal Nocturnal Hemoglobinuria

HLA evolutionary divergence (HED) is a continuous metric that quantifies the breadth of the immunopeptidome that can be presented by an individual's HLA allotype. High HED scores have been shown to be associated with better outcome after immune check point inhibitor therapy in solid tumors.1 However, the role of HED has never been assessed in autoimmune disorders, and may have an impact on disease susceptibility and outcomes. Here we explored the impact of HED on clinical features of aplastic anemia (AA) and paroxysmal nocturnal hemoglobinuria (PNH). The immunological landscape of those diseases is characterized by an HLA-restricted CD8+ and CD4+ mediated autoimmunity which leads to hematopoietic stem cell destruction, with a crucial role played by immune-dominant PNH clones and immune escape mechanisms likely associated with the down-regulation of the HLA-antigen presentation. Since higher HED scores reflect a wider antigenic spectrum and potentially more diverse peptide presentation capabilities, we hypothesize that this context not only may elicit T-cellular responses by auto-antigen presentation but also that HLA structural diversity can impact on disease phenotype and have a role within the definition of an immune-dominant (higher HED) or immune-escape (lower HED) environment. Using an NGS-based platform targeting the entire HLA locus, we have sequenced DNA samples of a cohort of 98 well-annotated AA, PNH, or AA/PNH patients. We then calculated HED at the classical HLA class I and II loci (A, B, C, DRB1, DQA1, DQB1, DPB1, DPA1), and investigated its impact on disease course and outcomes (Fig. A, B). Homozygosity for at least 1 out of 8 loci was frequently found (70%), especially for class II, however only 2% of patients had &amp;gt;1 homozygous locus). HLA-B and HLA-DQA1 genotypes demonstrated the highest HED among HLA-I and II loci, respectively (Fig. C). While for class I loci no difference was detected across diagnostic subgroups, mean HED for class II loci was significantly lower for PNH patients as compared to AA (6.031 vs 7.623 respectively p=0.047). Analysis of HED metrics across several binary outcomes within logistic regression models demonstrated that higher HED at class I and class II loci was generally associated with unfavorable disease characteristics and response outcomes. Specifically, high mean HED in class I and particularly in B and C loci tracked with disease severity (severe/very severe AA according to modified Camitta criteria: OR= 1.36 [95%CI 1.12, 1.70], p=0.003),2,3 whereas higher mean HED in class II was associated with refractoriness to immunosuppression [OR=1.18 (95%CI: 1.01-1.42), p=0.041]. In particular, a strong relationship was found for DQB1 locus [p=0.032, OR=1.12 (95%CI: 1.01-1.25)] in severe AA patients. Moreover, high HED in DPB1 was associated with early disease presentation [OR= 1.32 (95%CI 1.02, 1.80), p=0.047]. No correlation was found with overall survival. In summary, our results indicate that higher HED scores correlate with severity, early disease onset and refractoriness to immune-suppression in AA patients. High HED may increase the probability of presenting self-peptides that elicit dominant autoimmune T cell responses. Consistent with this line of reasoning, it is not surprising that lower HED (for class II HLA) is found in PNH subjects and that disruptive HLA somatic mutations in AA are preferably found in loci with increased structural diversity, consistent with the idea that less diversity may produce more immune-escape (see Abstract #: 142501). Our results suggest that HED may be useful for risk stratification of patients with immune-mediated bone marrow failure disorders, and more generally, that the ability to present a wider antigenic peptide spectrum may produce a more pervasive autoimmune response. Disclosures Patel: Alexion: Other: educational speaker. Saunthararajah:EpiDestiny: Consultancy, Current equity holder in private company, Patents &amp; Royalties: University of Illinois at Chicago.

Dog leucocyte antigen (DLA) class II haplotypes and risk of canine diabetes mellitus in specific dog breeds

BackgroundCanine diabetes mellitus (DM) is a common endocrine disease in domestic dogs. A number of pathological mechanisms are thought to contribute to the aetiopathogenesis of relative or absolute insulin deficiency, including immune-mediated destruction of pancreatic beta cells. DM risk varies considerably between different dog breeds, suggesting that genetic factors are involved and contribute susceptibility or protection. Associations of particular dog leucocyte antigen (DLA) class II haplotypes with DM have been identified, but investigations to date have only considered all breeds pooled together. The aim of this study was to analyse an expanded data set so as to identify breed-specific diabetes-associated DLA haplotypes.MethodsThe 12 most highly represented breeds in the UK Canine Diabetes Register were selected for study. DLA-typing data from 646 diabetic dogs and 912 breed-matched non-diabetic controls were analysed to enable breed-specific analysis of the DLA. Dogs were genotyped for allelic variation at DLA-DRB1, -DQA1, -DQB1 loci using DNA sequence-based typing. Genotypes from all three loci were combined to reveal three-locus DLA class II haplotypes, which were evaluated for statistical associations with DM. This was performed for each breed individually and for all breeds pooled together.ResultsFive dog breeds were identified as having one or more DLA haplotype associated with DM susceptibility or protection. Four DM-associated haplotypes were identified in the Cocker Spaniel breed, of which one haplotype was shared with Border Terriers. In the three breeds known to be at highest risk of DM included in the study (Samoyed, Tibetan Terrier and Cairn Terrier), no DLA haplotypes were found to be associated with DM.ConclusionsNovel DLA associations with DM in specific dog breeds provide further evidence that immune response genes contribute susceptibility to this disease in some cases. It is also apparent that DLA may not be contributing obvious or strong risk for DM in some breeds, including the seven breeds analysed for which no associations were identified.

Genetic diversity, evolution and selection in the major histocompatibility complex DRB and DQB loci in the family Equidae

BackgroundThe mammalian Major Histocompatibility Complex (MHC) is a genetic region containing highly polymorphic genes with immunological functions. MHC class I and class II genes encode antigen-presenting molecules expressed on the cell surface. The MHC class II sub-region contains genes expressed in antigen presenting cells. The antigen binding site is encoded by the second exon of genes encoding antigen presenting molecules. The exon 2 sequences of these MHC genes have evolved under the selective pressure of pathogens. Interspecific differences can be observed in the class II sub-region. The family Equidae includes a variety of domesticated, and free-ranging species inhabiting a range of habitats exposed to different pathogens and represents a model for studying this important part of the immunogenome. While equine MHC class II DRA and DQA loci have received attention, the genetic diversity and effects of selection on DRB and DQB loci have been largely overlooked. This study aimed to provide the first in-depth analysis of the MHC class II DRB and DQB loci in the Equidae family.ResultsThree DRB and two DQB genes were identified in the genomes of all equids. The genes DRB2, DRB3 and DQB3 showed high sequence conservation, while polymorphisms were more frequent at DRB1 and DQB1 across all species analyzed. DQB2 was not found in the genome of the Asiatic asses Equus hemionus kulan and E. h. onager. The bioinformatic analysis of non-zero-coverage-bases of DRB and DQB genes in 14 equine individual genomes revealed differences among individual genes. Evidence for recombination was found for DRB1, DRB2, DQB1 and DQB2 genes. Trans-species allele sharing was identified in all genes except DRB1. Site-specific selection analysis predicted genes evolving under positive selection both at DRB and DQB loci. No selected amino acid sites were identified in DQB3.ConclusionsThe organization of the MHC class II sub-region of equids is similar across all species of the family. Genomic sequences, along with phylogenetic trees suggesting effects of selection as well as trans-species polymorphism support the contention that pathogen-driven positive selection has shaped the MHC class II DRB/DQB sub-regions in the Equidae.

Revisiting the association between human leukocyte antigen and end-stage renal disease.

Multiple works have studied possible associations between human leukocyte antigen (HLA) alleles and end stage renal disease (ESRD) showing, however, contradictory and inconsistent results. Here, we revisit the association between ESRD and HLA antigens, comparing HLA polymorphism (at HLA-A, -B, -C, -DRB1, -DQB1 and DQA1 loci) in ESRD patients (n = 497) and controls (n = 672). Our data identified several HLA alleles that displayed a significant positive or negative association with ESRD. We also determined whether heterozygosity or homozygosity of the ESRD-associated HLA alleles at different loci could modify the prevalence of the disease. Few HLA allele combinations displayed significant associations with ESRD, among which A*3_26 combination showed the highest strength of association (OR = 4.488, P≤ 0.05) with ESRD. Interestingly, the age of ESRD onset was not affected by HLA allele combinations at different loci. We also performed an extensive literature analysis to determine whether the association of HLA to ESRD can be similar across different ethnic groups. Our analysis showed that at least certain HLA alleles, HLA-A*11, HLA-DRB1*11, and HLA-DRB1*4, display a significant association with ESRD in different ethnic groups. The findings of our study will help in determining possible protective or susceptible roles of various HLA alleles in ESRD.

Polymorphism of HLA-A, -B, -C, -DRB1 and -DQB1 Allele and Haplotype Frequency at High Resolution in Guangxi Zhuang Population

To analyze the characteristics of allelic and haplotypic polymorphisms of human leukocyte antigens at HLA-A, -B, -C, DRB1 and DQB1 loci in Guangxi Zhuang population. Polymerase chain reaction-sequence based typing (PCR-SBT) was used to detect. The five loci (HLA-A, -B, -C, -DRB1, -DQB1) in 350 unrelated Zhuang ethnic individual from Guangxi region. Allelic and haplotypic frequencies were calculated by using Arlequin software 3.5.2.2. Phylogeny tree were constructed by using MEGA software 6.0, and SPSS software was used for principal component analysis. Among the five loci in the population, only HLA-A and DRB1 loci were observed as departures from Hardy-Weinberg expectations. A total of 19 HLA-A, 42 HLA-B, 22 HLA-C, 25 HLA-DRB1 and 15 HLA-DQB1 alleles were found in 350 samples. The most highest frequent alleles were A*11: 01(28.57%), B*46: 01(14.00%), C*01: 02(18.43%), DRB1*16: 02 (15.71%）and DQB1*05: 02 (35.00%) . The most common five loci haplotype was A*33: 03-C*03: 02-B*58: 01-DRB1*03: 01-DQB1*02: 01（6.86%）. The phylogenetic tree analysis showed that Guangxi Zhuang population had a relative close genetic relationship with southern Han Chinese populations. This reaserch found that the HLA-A, B, C, DRB1 and DQB1 loci are highly polymorphic in Guangxi Zhuang population.

Association of HLA-A, -B, -C, -DRB1 and -DQB1 alleles at amino acid level in individuals with schizophrenia: A study from South India.

Schizophrenia, a chronic severe psychiatric illness of unknown aetiology, has been shown to be associated with HLA alleles but at varied degree in different population. The present study has focussed on analysing the frequency of HLA class I and class II alleles in persons with schizophrenia from South India. Ninety seven individuals with schizophrenia and 103 age- and gender-matched controls were typed for HLA- A, B, C, DRB1 and DQB1 loci by next-generation sequencing in Illumina MiniSeq using MIA FORA NGS FLEX HLA typing kit. The results showed that HLA-A*01:01:01, B*37:01:01 and C*01:02:01 were positively associated with schizophrenia while HLA-B*35:03:01 and DRB1*04:03:01 were negatively associated. Gender-specific associations revealed that DRB1*10:01:01 and DQB1*05:01:01 were positively associated while DQB1*03:02:01 was negatively associated with female subjects with schizophrenia. A*24:02:01~B*37:01:01~C*06:02:01~DRB1*10:01:01~DQB1*05:01:01 is the predominant haplotype in schizophrenia population when compared to healthy controls. Amino acid association in susceptible and protective alleles has shown that the presence of peptide in the peptide-binding groves of mature HLA-A protein (K, M, V, R and V at 44th, 67th, 150th, 156th and 158th position), HLA-B protein (D and S at 77th and 99th position) and HLA-C protein (M at 99th position) confer susceptibility to the disease, only in the absence of E (Glutamic acid) at 74th position in mature HLA-DRB1 protein. Interaction of amino acids in protective alleles namely B*35:01:01 and DRB1*04:03:01 has revealed that aspartic acid at 114th (D) position in mature HLA-B protein and glutamic acid (E) at 74th position of mature HLA-DRB1 protein have a combined effect in protecting against the disease. The study has revealed the HLA association with schizophrenia in south Indian population. The amino acid interaction with the disease needs to be confirmed in a larger population.

Substituting imputation of HLA antigens for high-resolution HLA typing: Evaluation of a multiethnic population and implications for clinical decision making in transplantation.

Molecular mismatch analysis for assessment of histocompatibility in transplantation requires high-resolution HLA typing. Algorithms to "guesstimate" high-resolution from low-resolution typing exist, but their accuracy remains unknown. We converted high-resolution, sequence-based, HLA typing of 310 subjects from an ethnically heterogeneous population to low-resolution equivalents and tested the ability of the NMDP HaploStats and HLA Matchmaker programs to impute/reproduce the measured high-resolution HLA type, using the more common "winner-takes-all" approach. Only 35.6% of the HaploStats imputed HLA-A, -B, -C, -DRB1, and -DQB1 haplotypes had no mistakes, and the accuracy was significantly lower for non-Caucasians (29.1%) compared to Caucasians (45.2%) (odds ratio [OR], 0.5; 95% confidence interval [CI], 0.3-0.8; P=.004). HLA Matchmaker was not able to provide high-resolution haplotypes for 45.2% of Caucasian subjects and 63.5% of non-Caucasian subjects (P=.002). Of those with an imputed result, only 10.3% of Caucasians and 4.8% of non-Caucasians had accurate 10-allele high-resolution output. Eplet analysis revealed additional, inaccurate eplets in 37% of individuals, with 22.5% showing at least 2 additional, inaccurate eplets; incorrect eplets were more common among non-Caucasians (OR, 1.8; 95% CI, 1.1-2.9; P=.018). Given this high error rate, caution should be taken before using imputation tools for clinical or research purposes, especially for non-Caucasian individuals.

Latitudinal diversity gradient and cetaceans from the perspective of MHC genes.

Pathogen diversity is a key source of selective pressure on immune system genes, shaping molecular evolution mainly on widely distributed or migratory organisms such as cetaceans. Here, we investigated the effects of latitudinal span migration, different biomes occupation, and pathogen-mediated selection on MHC DQB locus divergence on cetaceans. We applied some evolutionary genetics methods using a dataset of 15 species and 121 sequences, and we found a trend on greater MHC divergence on tropical species when compared with either temperate or migratory species. In addition, oceanic cetaceans exhibit greater MHC divergence. Here, we show that, despite there was a correlation between the diversity of MHC DQB alleles with the distribution of organisms, the pattern of diversity found is not completely explained by pathogenic pressure, suggesting that other factors must be investigated for a better understanding of the processes related to the diversity of MHC in cetaceans.

AB0013 HLA ASSOCIATION WITH SYSTEMIC SCLEROSIS (SSc) IN NORTH INDIAN POPULATION AND FAMILIAL INHERITANCE PATTERNS

Background:It is widely believed that SSc develops in an individual with a permissive genetic makeup.Genetic influences have long been suspected to impact SSc. In families with a history of SSc, the incidence of disease can range from 1.5 to 1.7% (1). There are several reports of familial occurrence and certain alleles of the HLA system have been associated with the disease (2).No Indian data pertaining to genetic basis of systemic sclerosis is present. Understanding the genetic basis of the disease will help us in defining the biomarkers of the disease in the population that can help in early diagnosis and prognosis.Objectives:To study HLA association with Systemic sclerosis (SSc) in North Indian Population and its genetic susceptibility to familial systemic sclerosis.Methods:A total of 150 SSc patients diagnosed by following ACR and EULAR criteria and 150 control subjects, were genotyped for HLA-A, B, DRB1, DQB1 loci by Luminex® 200 Instrument (USA). The association of alleles with disease susceptibility was tested by Chi-square test and Fisher’s exact test.HLA Typing for HLA class I (A, B, C) and II(DR,DQ,DP) for familial study of systemic sclerosis in 2 families was performed by Next Generation Sequencing(NGS) with illumina MiniSeq using MIA FORA NGS Kits from IMMUCOR. Antinuclear patterns (ANA) and specific antibodies were detected by indirect Immunofluorescence and Immunoblot (Euroline, Germany).Results:Strong disease associations were observed for haplotypes A*24(OR=1.7;&lt; 0.02), A*32(OR=2.8;&lt; 0.02), B*35(OR=1.7;&lt; 0.03), DRB1*11(OR=2.1;&lt; 0.007). The reduced frequencies of haplotypes A*68(P&lt; 0.05), DRB1*10(P&lt; 0.05), DRB1*12 (P&lt;0.00) among patients suggested a protective association. There was no statistical association found with HLA DQB*1.Through NGS we observed that in the 1stfamily haplotypes HLA –A*11, 32, 24; B* 51, 55, 35; C*-14, 04; DRB1*15, 04; DQB1*05, 03; DPB1*04, 26 appears in affected family members with serological abnormalities.In the 2ndfamily both mother and daughter had same set of haplotypes except DQB1 with serological abnormalities. The haplotypes DPB1*04 was present in all the diseased individuals of both the families (Fig. 1 and table 1).Table 1.NGS HLA typing reportABCDRB1DQB1DPB1F111 2435 1504 0415 1505 0502 26F211 3251 5514 0415 0405 0304 04F311 2435 5504 0415 1505 0526 04F432 1151 1514 0415 0405 0302 04F524 3335 4404 0715 0705 0226 14F611 2435 5504 0415 1505 0504 26F711 2435 5504 0415 1505 0504 26F824 3251 3514 0404 1503 0526 04F911 3251 5514 0415 0405 0304 04F1011 3344 5207 1211 0702 0304 13F1111 3344 5207 1211 0703 0304 13Fig. 1Conclusion:The risk alleles A*24, 32; B*35; DRB1*11 were found to be associated with North Indian cohort of SSc, while the protecting alleles were A*68; DRB1*10, 12.These risk alleles were present in the SSc affected family members and the protective alleles were absent in the same. Surprisingly, even healthy members carried the same risk alleles but did not manifest the disease or have serological evidence of the same. We have not excluded occurrence of disease at a later age, as presently the healthy siblings are young. Thus our study indicates that though HLA association are found with SSc but many other factors like HLA (HLA *C, DPB1*) or non HLA genes as wells as epigenetic factors might also play a role in disease manifestation and severity.

HLA-A, -B, -C, -DRB1 and -DQB1 alleles and haplotypes in 271 Southeast Asia Indians from Peninsular Malaysia

A total of 271 Southeast Asia Indians from Peninsular Malaysia were genotyped for HLA-A, -B, -C, -DRB1, and -DQB1 loci using polymerase chain reaction sequence-specific oligonucleotide probe hybridization methods. In this report, HLA-B and HLA-DQB1 was in Hardy-Weinberg proportions (HWEP) (p > 0.05). We observed significant deviation from the HWEP for HLA-A (p < 0.05), HLA-C (p < 0.01) and HLA-DRB1 (p < 0.01) loci. This genotype data is available in Allele Frequencies Network Database (AFND) Dos Santos et al. (2016).

Compatibility at amino acid position 98 of MICB reduces the incidence of graft-versus-host disease in conjunction with the CMV status.

Graft-versus-host disease (GVHD) and cytomegalovirus (CMV)-related complications are leading causes of mortality after unrelated-donor hematopoietic cell transplantation (UD-HCT). The non-conventional MHC class I gene MICB, alike MICA, encodes a stress-induced polymorphic NKG2D ligand. However, unlike MICA, MICB interacts with the CMV-encoded UL16, which sequestrates MICB intracellularly, leading to immune evasion. Here, we retrospectively analyzed the impact of mismatches in MICB amino acid position 98 (MICB98), a key polymorphic residue involved in UL16 binding, in 943 UD-HCT pairs who were allele-matched at HLA-A, -B, -C, -DRB1, -DQB1 and MICA loci. HLA-DP typing was further available. MICB98 mismatches were significantly associated with an increased incidence of acute (grade II-IV: HR, 1.20; 95% CI, 1.15 to 1.24; P < 0.001; grade III-IV: HR, 2.28; 95% CI, 1.56 to 3.34; P < 0.001) and chronic GVHD (HR, 1.21; 95% CI, 1.10 to 1.33; P < 0.001). MICB98 matching significantly reduced the effect of CMV status on overall mortality from a hazard ratio of 1.77 to 1.16. MICB98 mismatches showed a GVHD-independent association with a higher incidence of CMV infection/reactivation (HR, 1.84; 95% CI, 1.34 to 2.51; P < 0.001). Hence selecting a MICB98-matched donor significantly reduces the GVHD incidence and lowers the impact of CMV status on overall survival.

HLA-A, -B, -DRB1 and -DQB1 polymorphisms among Iraqi Arabs

In this report, HLA polymorphisms (A, B, DRB1 and DQB1 loci) were determined in 149 unrelated Iraqi Arab potential bone marrow and kidney donors. Molecular genotyping was carried out by polymerase chain reaction followed by specific oligonucleotide probe hybridizations. Data were analyzed by Arlequin software. HLA-A, -B and -DRB1 genotype frequencies were significantly deviated from Hardy-Weinberg equilibrium, while HLA-DQB1 frequencies showed no deviation. A*03, B*35, DRB1*11 and DQB1*02 were the most frequent allele groups, while A*02-B*07-DRB1*04-DQB1*03 was the most frequent haplotype. HLA data are available in the Allele Frequencies Net Database (AFND: 3680) under the population name “Iraq Arabs”.