The novel HLA-DQA1*05:05:17:03 allele, identified in a potential organ donor

HLA-DQA1*05:05:17:03 differs from HLA-DQA1*05:05:01:02 by a single base substitution in exon 1 and HLA-DQA1*05:05:17:01 within introns 1 and 2.

The novel HLA-C*06:372 allele, identified in a stem cell donor of an old order mennonite ethnicity

HLA-C*06:372 differs from HLA-C*06:02:01:01 by a single substitution in exon 4.

Host genetic variants, Epstein-Barr virus subtypes, and the risk of nasopharyngeal carcinoma: Assessment of interaction and mediation

Epstein-Barr virus (EBV) and human leukocyte antigen (HLA) polymorphisms are well-known risk factors for nasopharyngeal carcinoma (NPC). However, the combined effects between HLA and EBV on the risk of NPC are unknown. We applied a causal inference framework to disentangle interaction and mediation effects between two host HLA SNPs, rs2860580 and rs2894207, and EBV variant 163364 with a population-based case-control study in NPC-endemic southern China. We discovered the strong interaction effects between the high-risk EBV subtype and both HLA SNPs on NPC risk (rs2860580, relative excess risk due to interaction [RERI] = 4.08, 95% confidence interval [CI] = 2.03-6.14; rs2894207, RERI = 3.37, 95% CI = 1.59-5.15), accounting for the majority of genetic risk effects. These results indicate that HLA genes and the high-risk EBV have joint effects on NPC risk. Prevention strategies targeting the high-risk EBV subtype would largely reduce NPC risk associated with EBV and host genetic susceptibility.

Association of HLA gene polymorphisms with Helicobacter pylori related gastric cancer-a systematic review

The appropriate host cell immune responses for the progression of several diseases, including gastric or stomach cancer (GC), are significantly influenced by HLA polymorphisms. Our objective was to systematically review the evidence linking HLA polymorphisms with the risk of Helicobacter. pylori related GC. We conducted a comprehensive literature search to identify studies published between 2000 and April 2023 on the association of HLA polymorphisms with H. pylori related GC using databases such as Medline through PubMed, Embase, Web of Science (core collection), The Cochrane Library, and Scopus. Two authors independently screened articles, extracted data, and assessed the risk of bias using the Risk of Bias Assessment tool for Non-randomized Studies. From 7872 retrieved studies, 19 met inclusion criteria, encompassing 1656 cases and 16,787 controls across four World Health Organization regions, with Japan contributing the most studies. We explored HLA-A/B/C, HLA-DRB1/DQA1/DQB1, HLA-G, and MICA alleles. Of 29 significant HLA polymorphisms identified, 18 showed a positive association with GC, whereas 11 were negatively associated. HLA-DQB1*06 allele was most frequently associated to susceptibility, as reported in four studies, followed by HLA-DRB1*04 and HLA-DQA1*01, each reported in two studies. Conversely, HLA-G*01, HLA-DQA1*01, HLA-DQA1*05, and HLA-DQB1*03 were identified as protective in two studies each. Additionally, five genotypes and six haplotypes were reported as positive, whereas three genotypes and two haplotypes were negative factors for the disease incidence or mortality. Despite heterogeneity in the study population and types of HLA polymorphisms examined, our analysis indicates certain polymorphisms are associated with H. pylori related GC progression and mortality in specific populations.

The novel HLA-DRB1*08:127 allele, identified in a deceased organ donor of Scandinavian descent

HLA-DRB1*08:127 differs from HLA-DRB1*08:01:01:01 by a single substitution in exon 4.

HLA-targeted sequencing reveals the pathogenic role of HLA-B*15:02/HLA-B*13:01 in albendazole-induced liver failure: a case report and a review of the literature

Drug-induced liver injury (DILI) is one of the serious adverse drug reactions (ADRs), which belongs to immune-mediated adverse drug reactions (IM-ADRs). As an essential health drug, albendazole has rarely been reported to cause serious liver damage. A young man in his 30 s developed severe jaundice, abnormal transaminases, and poor blood coagulation mechanism after taking albendazole, and eventually developed into severe liver failure. The patient was found heterozygous of HLA-B*15:02 and HLA-B*13:01 through HLA-targeted sequencing, which may have a pathogenic role in the disease. This case report summarizes his presentation, treatment, and prognosis. A useful summary of the diagnosis and associated genetic variant information is provided.

Analysis of somatic mutations and key driving factors of cervical cancer progression

We investigated the somatic mutations and key driving factors of cervical cancer by whole exome sequencing . We found 22,183 somatic single nucleotide variations (SNVs) in 52 paired samples. Somatic SNVs in cervical cancer were significantly higher than those in high-grade intraepithelial lesion and low-grade squamous intraepithelial lesion groups (P < 0.05). C → T/G accounted for 44.12% of base substitution. Copy number variation (false discovery rate < 0.05) was found in 57 chromosome regions. The three regions with significant differences between cervical cancer and non-cervical cancer groups were 1q21.1, 3q26.33, and 13q33.1, covering genes related to tumor proliferation, differentiation, and apoptosis. The frequency of human papillomavirus (HPV) insertion/integration and the number of "tCw" mutations in the cervical cancer group were significantly higher than those in the non-cervical cancer group (P < 0.05). The total number of mutations was positively correlated with the number of "tCw" mutations (R 2 = 0.7967). HPV insertion/integration (OR = 2.302, CI = 1.523-3.589, P = 0.0005), APOBEC enrichment (OR = 17.875, CI = 2.117-150.937, P = 0.001), and HLA-B*39 in HLA-I (OR = 6.435, CI = 0.823-48.919, P = 0.0042) were risk factors for cervical cancer, while HLA-DQB1*05 in HLA-II was a protective factor (OR = 0.426, CI = 0.197-0.910, P = 0.032). Conclusively, HPV insertion/integration, APOBEC mutagenesis, and HLA polymorphisms are high-risk factors for cervical cancer and may be causes of genome instability and somatic mutations. This study provides experimental data for revealing the molecular mechanism of cervical cancer.

Association between human leukocyte antigen (HLA) and end-stage renal disease (ESRD): a meta-analysis

Objectives

We recently studied the association between various human leukocyte antigen (HLA) alleles and end-stage renal disease (ESRD). According to our analysis, HLA-B*50 and HLA-DQA1*3 alleles were positively associated with ESRD, while B*40, DRB1*12, DRB1*13, and DQA1*6 alleles were negatively associated with ESRD. However, a single case-control study does not have enough statistical power to evaluate the possible impact of genetic polymorphism on any disease. Hence, the main objective of this meta-analysis is to determine the association between these abovementioned HLA alleles and ESRD.

Design

MEDLINE/PubMed, EMBASE, Web of Science, and Cochrane databases were searched through December 2020 for case-control studies on the associations between HLA polymorphisms and ESRD. Independent reviewers screened the texts of potentially eligible studies and assessed the risk of bias. The meta-analysis was conducted based on the checklists and guidelines based on PRISMA.

Results

We identified 26 case-control studies comprising 1,312 ESRD and 3,842 healthy subjects. A non-significant positive association was observed between HLA-B*50 (OR = 1.02, 95% CI [0.90, 1.24]), HLA-B*40 (OR = 1.75, 95% CI [0.98, 3.2]), HLA-DQA1*3, (OR = 1.17, 95% CI [0.74, 1.84]), DRB1*12 (OR = 1.05, 95% CI [0.94, 1.18]) alleles and ESRD. In addition, a non-significant negative association was observed between HLA-DRB1*13 (OR = 0.90, CI [0.81, 1.01]), HLA-DQB1*6 (OR = 0.79, 95% CI [0.58, 1.07]) alleles and ESRD.

Conclusions

Our meta-analysis indicates no significant association between HLA-B*50, HLA-DQA1*3, B*40, DRB1*12, DRB1*13, and DQA1*6 alleles and ESRD. Further studies with larger sample sizes and adjustments for confounders are required to confirm these conclusions.

HLA pharmacogenetic markers of drug hypersensitivity from the perspective of the populations of the Greater Middle East

Specific HLA associations with drug hypersensitivity may vary between geographic regions and ethnic groups. There are little to no data related to HLA-drug hypersensitivity on populations who reside in the Greater Middle East (GME), a vast region spanning from Morocco in the west to Pakistan in the east. In this review, the authors intended to summarize the significant HLA alleles associated with hypersensitive drug reactions induced by different drugs, as have been found in different populations, and to summarize the prevalence of these alleles in the specific and diverse populations of the GME. For example, HLA-B*57:01 allele prevalence, associated with abacavir-induced hypersensitivity, ranges from 1% to 3%, and HLA-DPB1*03:01 prevalence, associated with aspirin-induced asthma, ranges from 10% to 14% in the GME population. Studying pharmacogenomic associations in the ethnic groups of the GME may allow the discovery of new associations, confirm ones found with a low evidence rate and enable cost-effectiveness analysis of allele screening before drug use.

Physiopathology and effectiveness of therapeutic vaccines against human papillomavirus

Human papillomavirus (HPV) is a well-known sexually transmitted disorder globally. Human papillomavirus (HPV) is the 3rd most common cancer that causes cervical carcinoma, and globally it accounts for 275,000 deaths every year. The load of HPV-associated abrasions can be lessened through vaccination. At present, three forms of prophylactic vaccines, Cervarix, Gadrasil, and Gardasil 9, are commercially accessible but all these prophylactic vaccines have not the ability to manage and control developed abrasions or infections. Therefore, a considerable amount of the population is not secured from HPV infectivity. Consequently, the development of therapeutic HPV vaccines is a crucial requirement of this era, for the treatment of persisting infections, and to stop the progression of HPV-associated cancers. Therapeutic vaccines are a developing trial approach. Because of the constitutive expression of E6 and E7 early genes in cancerous and pre-cancerous tissues, and their involvement in disturbance of the cell cycle, these are best targets for this therapeutic vaccine treatment. For the synthesis and development of therapeutic vaccines, various approaches have been examined comprising cell-based vaccines, peptide/protein-based vaccines, nucleic acid-based vaccines, and live-vector vaccines all proceeding towards clinical trials. This review emphasizes the development, progress, current status, and future perspective of several vaccines for the cure of HPV-related abrasions and cancers. This review also provides an insight to assess the effectiveness, safety, efficacy, and immunogenicity of therapeutic vaccines in the cure of patients infected with HPV-associated cervical cancer.

Association between HLA genotype and ferritin levels in COVID-19 infection: a study of a Saudi cohort

BACKGROUND

An elevation in serum ferritin levels through an unknown mechanism was observed in COVID-19 infected patients. This study examined the association between patients' HLA genotype and serum ferritin level modulation and also assessed the effect of serum ferritin levels on infection severity/mortality.

MATERIALS AND METHODS

One hundred and thirty-six COVID-19 Saudi patients were divided into two groups according to their ferritin levels: group 1 (<500 ng/mL, N = 67) and group 2 (>500 ng/mL, N = 69). HLA genotyping (class I and II) was carried out through the rPCR-SSO method.

RESULTS

High serum ferritin levels were associated with a significant increase in infection severity, as 75% of ICU patients showed high levels of ferritin compared to 43% of patients with moderate symptoms, p = .002. This elevation indicated a gender skew in that 56% of the infected male patients displayed high ferritin levels compared to 36.6% of the female patients, p = .03. In terms of mortality, 74% of patients with fatal outcomes had a high level of serum ferritin compared to 47% of recovered patients, p = .039. There was a significant difference in the HLA frequency between the two groups, with a predominance of HLA-A*01 in the low-ferritin group (19.4 vs. 6.5%, p = .002, p_c = .016) and predominance of C*03 in the high ferritin group (10.9 vs. 3%, p = .047, p_c = .27).

CONCLUSION

High serum ferritin levels are associated with an increase in COVID-19 severity, which may be affected by HLA polymorphism.

Characterization of the novel HLA-A*03:01:102 allele by next-generation sequencing

HLA-A*03:01:102 differs from HLA-A*03:01:01:01 by one nucleotide substitution at position 72 in exon 1.

HLA-A, -C, -B, -DRB1, -DQA1, and -DQB1 Allele and Haplotype Repertoires in the Albanian Population from Kosovo

To give new insight into the huge polymorphism of HLA system and supplement the existing data, an analysis of HLA alleles and HLA-A~C~B~DRB1~DQA1~DQB1 haplotype distribution in 124 Albanian individuals from Kosovo was performed. All samples were HLA-typed applying the polymerase chain reaction-sequence specific oligonucleotide probing (PCR-SSOP) method and all ambiguous HLA typing results were additionally confirmed by the standard PCR-Sequence Specific Primers (PCR-SSP) high-resolution protocol. Twenty-two HLA-A, 21 HLA-C, 37 HLA-B, 27 HLA-DRB1, 11 HLA-DQA1 and 14 HLA-DQB1 allele groups were detected. Sixteen out of 172 different six-locus estimated haplotypes were found at a frequency higher than 1.00% with a cumulative frequency of 28.82%. The most prevalent haplotype was found to be HLA-A*02:01~C*07:01~B*18:01~DRB1*11:04~DQA1*05:05~DQB1*03:0(5.2%).A total of 13 haplotypes were observed with higher frequency than in populations reported in HaploStats and The Allele Frequency Net Database. The proposed origin of the most frequent haplotypes reflects a basic Euro-Mediterranean background of Albanians in Kosovo. This is the first report of high-resolution HLA-A~C~B~DRB1~DQA1~DQB1 haplotype distribution among the Albanian population from Kosovo, which provides valuable anthropological data and confirms population-specific characteristics.

Frequency of HLA alleles among COVID-19 infected patients: Preliminary data from Saudi Arabia

HLA polymorphism is one of the genetic factors that may be associated with variations in susceptibility to COVID-19 infection. In this study, the frequency of HLA alleles among Saudi patients infected with COVID-19 was examined. The association with infection susceptibility and mortality was evaluated. This study included 135 Saudi COVID-19-infected patients (106 recovered and 29 died) who were admitted to hospitals because of their symptoms, and 135 healthy controls. HLA class I (A, B, C) and class II (DRB1, DQB1) genotyping was performed using the molecular method (PCR-rSSO). In this study, there was a significant increase in the frequency of HLA-A*01, B*56 and C*01 among infected patients compared to the control group (12.1% vs. 5.2%, p = 0.004, 3.7% vs. 0%, p = 0.006, 4.4% vs. 1.5%, p = 0.042, respectively). Moreover, there was a significant increase in the frequency of HLA-A*03 and C*06 among fatal patients compared to infected patients (13.8% vs. 5.7%, p = 0.036, 32.8% vs. 17.5%, p = 0.011, respectively). In terms of HLA class II, HLA-DRB1*04 was significantly higher in the control group compared to infected patients (27.4% vs. 16.3%, p = 0.002), while HLA-DRB1*08 was significantly higher in the infected group compared to the control (4.8% vs. 0.7%, p = 0.004). After statistical correction of the p value, A*01, B*56, DRB1*04 and DRB1*08 remained statistically significant (p_c = 0.04, p_c = 0.03, p_c = 0.014 and p_c = 0.028). This initial data suggested that individual HLA genotypes might play a role in determining susceptibility to COVID-19 infection and infection outcome. However, examining a larger sample size from different populations is required to determine a powerful association for clinical application.

Characterization of two new human leukocyte antigen alleles: HLA-A*02:982 and HLA-C*04:441

Two new alleles were identified during routine next generation sequencing.

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.

HLA-A, -B, -C, -DRB1 and -DQB1 allele and haplotype frequencies and phylogenetic analysis of Bahraini population

The origin of Arab-speaking population is classified according to their geographical location, ethnic background, and historical influx of nearby and distant populations. Data on HLA class I and class II loci in (Arabian Peninsula) Bahraini population are lacking. We analyzed HLA genetic profile of Bahrainis with neighboring communities, and with Levantines, North Africans, Sub-Saharans, Europeans, and Asians, using genetic distances, neighbor-joining dendrograms, correspondence and haplotype analysis. HLA class I and class II genotyping were done by high resolution PCR-SSP in 175 Bahraini subjects. In total, 19 HLA-A, 33 HLA-B, 15 HLA-C, 14 DRB1 and 7 DQB1 alleles were identified. The most common class I alleles were A*02:01:01 (18.3%), A*01:01:01(15.4%), B*35:01:02 (12.9%), C*12:01:01 (15.1%), and C*04:01:01 (14.9%), while DRB1*03:01:01 (18.0%), DQB1*02:01:01 (29.1%), and DQB1*05:01:01 (24.9%) were the most frequent class II alleles. Significant linkage disequilibrium was seen between all HLA loci pairs. DRB1*03:01:01-DQB1*02:01:01 (15.18%) was the most frequent two-locus haplotype. Significant negative Fnd values were observed, indicating balancing selection at studied loci. Bahrainis appear to be related to Western Mediterranean (North Africans, Iberians and French), but relatively distinct from Levantines (Palestinians, Lebanese, and Jordanians) and Sub-Saharans. This indicates limited genetic contribution of Levantine Arabs and Sub-Saharans to the Bahraini gene pool.

A New Pedigree-Based SNP Haplotype Method for Genomic Polymorphism and Genetic Studies

Single nucleotide polymorphisms (SNPs) are usually the most frequent genomic variants. Directly pedigree-phased multi-SNP haplotypes provide a more accurate view of polymorphic population genomic structure than individual SNPs. The former are, therefore, more useful in genetic correlation with subject phenotype. We describe a new pedigree-based methodology for generating non-ambiguous SNP haplotypes for genetic study. SNP data for haplotype analysis were extracted from a larger Type 1 Diabetes Genetics Consortium SNP dataset based on minor allele frequency variation and redundancy, coverage rate (the frequency of phased haplotypes in which each SNP is defined) and genomic location. Redundant SNPs were eliminated, overall haplotype polymorphism was optimized and the number of undefined haplotypes was minimized. These edited SNP haplotypes from a region containing HLA-DRB1 (DR) and HLA-DQB1 (DQ) both correlated well with HLA-typed DR,DQ haplotypes and differentiated HLA-DR,DQ fragments shared by three pairs of previously identified megabase-length conserved extended haplotypes. In a pedigree-based genetic association assay for type 1 diabetes, edited SNP haplotypes and HLA-typed HLA-DR,DQ haplotypes from the same families generated essentially identical qualitative and quantitative results. Therefore, this edited SNP haplotype method is useful for both genomic polymorphic architecture and genetic association evaluation using SNP markers with diverse minor allele frequencies.

HLA Class II Allele and Haplotype Diversity in Libyans and Their Genetic Relationships with Other Populations

Background: Libya witnessed the succession of many civilizations and ethnic groups throughout history, thereby questioning the origin of present-day Libyans. Indeed, they were considered Africans given the geographical position of the country, Arabs at the cultural level, and Berbers because of the notable presence of Berber tribes. Genetic anthropology studies investigating the origin of Libyans were rarely reported, and thus little was known about the population structure of current Libyans, particularly at autosomic markers level. Methods: We examined HLA class II (DRB1, DQB1) gene profiles of 101 unrelated Libyans, and compared them with Arab-speaking communities and with Sub-Saharan and Mediterranean populations using Neighbour-Joining dendrograms, genetic distances, correspondence, and haplotype analysis. Results: Of the 42 DRB1 alleles identified, DRB1*07:01 (14.36%), DRB1*03:01 (12.38%) were the most frequent, while DQB1*02:01 (24.17%), DQB1*02:02 (13.86%), and DQB1*03:01 (12.38%) were the most frequent of the 17 DQB1 alleles detected. DRB1*03:01-DQB1*02:01 (6.93%), DRB1*07:01-DQB1*02:02 (4.45%), and DRB1*04:03-DQB1*03:02 (3.46%) were the most frequent DRB1-DQB1 haplotypes. Conclusion: Libyans appear to be closely related to North Africans, Saudis, and Iberians, but distinct from Levantine Arabs, East Mediterraneans, and Sub-Saharan Africans. This indicates limited genetic contribution of Levantine Arabs and Sub-Saharans on the makeup of Libyan gene pool. Our study confirmed genetic heterogeneity among Arab populations, with three identified groups. The first comprises North Africans, Saudis, and Kuwaitis who were related to Iberians and West Mediterraneans, while the second consists of Levantine Arabs who were close to East Mediterraneans, and the third contained Sudanese and Comorians, with a close relatedness to Sub-Saharans.

Associative role of HLA-DRB1 SNP genotypes as risk factors for susceptibility and severity of rheumatoid arthritis: A North-east Indian population-based study

Rheumatoid arthritis (RA) is a complex, multifactorial, systemic autoimmune disease. Reports are suggestive of the role of HLA especially HLA-DRB1 alterations in RA pathogenesis. Existing data involving different geographical populations on the role of alterations in specific locus of HLA-DRB1 in RA susceptibility and severity are equivocal, with no data available from ethnically distinct North-east Indian population, where RA cases are alarmingly increasing. This study aimed to evaluate the association of HLA-DRB1 gene SNPs (rs13192471, rs660895 and rs6457617) with susceptibility and severity of RA in an ethnically distinct North-east Indian population. Whole blood was collected from clinically characterized RA cases (satisfying the American College of Rheumatology 1987 criteria) (n = 123) and community-based age and sex-matched healthy controls (n = 156) with informed consent. The HLA-DRB1 SNP analysis was performed for all the RA and control cases using ARMS-PCR using case and control genomic DNA as template. Statistical analysis was performed by SPSSv13.0 software. The HLA-DRB1 rs660895 showed both wild (AA) and heterozygote (AG) genotype but the heterozygote allele was found to be associated with reduced risk of RA compared to controls [OR = 0.531, p = .024]. The difference in distribution of rs6457617 polymorphism between RA and control cases was comparable [OR = 0.525, p = .079]. Significantly higher distribution of variant rs13192471 genotype was observed in RA cases (69.92%) compared to controls (46.75%) (p < .001) and was associated with increased risk of susceptibility to RA [OR = 2.576, p < .001] compared to controls, as well as progression to severity in RA cases [OR = 2.404, p = .048]. Combinatorially also, the presence of rs13192471 variant genotype was associated with increased risk of RA susceptibility [OR = 8.267, p = .026] and RA severity [OR = 3.647, p = .280]. Alterations in HLA-DRB1 are associated with RA susceptibility. HLA-DRB1 rs13192471 SNP plays a critical role in RA susceptibility and severity in North-east Indian cases and has prognostic significance in RA.

Anthropological analysis of Tunisian populations as inferred from HLA class I and class II genetic diversity: A meta-analysis

Despite their importance, anthropological meta-analyses which allow for comprehensive evaluation of the relationships of a given population were rare. This meta-analysis evaluates the origin of Tunisians using polymorphic profile of HLA class I (A, B), and class II (DRB1, DQB1) genes, in historical, social and cultural context, and is the only analysis in the Middle East-North Africa (MENA) region. A total of 20 eligible populations were selected from several databases, and included representing 2553 Tunisian individuals, who were compared with Mediterranean and sub-Saharan populations. In total, 204 HLA alleles were detected in Tunisians, which comprised 54 HLA-A, 76 HLA-B, 50 DRB1, and 24 DQB1 alleles. The most frequent alleles were A*02:01(24.72%) in Berbers of Zrawa, B*50:01 (13.90.11%) in Tunisian-So, DRB1*07:01 (28.66%) in Ghannouchians, and DQB1*02:01 (42.79%) in Tunisians-H. The A, B, DRB, and DQB1 genotypes of 420 individuals were further subjected to a selection study. Despite the relatively large sample size, the loci depicted non-significant negative Fnd values, an indication of overall trend to balancing selection or gene flow. Except for Berbers of Djerba, dendrograms, correspondence analyses, genetic distances and haplotype analysis demonstrated the close relatedness of Berbers, Southern and Northern Tunisians, and strong relatedness was evident to Western Mediterranean, North African and Iberian populations, but not Sub-Saharans and Eastern Mediterranean populations, including Arabs. Collectively, this suggests that the contribution of Arabs and sub-Saharans to the present Tunisian gene pool is low. In addition, all Mediterranean populations depict a typical Mediterranean substratum, except for Greeks.

Association between chronic hepatitis B virus infection and HLA-DP gene polymorphisms in the Turkish population

AIM

Hepatitis B virus (HBV) affects approximately 360 million people worldwide. 10-15% of patients with chronic HBV develop liver cirrhosis (LC), liver failure and hepatocellular carcinoma (HCC). Chronic HBV infection or HBV clearance is influenced by both viral and host factors. In genome-wide association studies (GWAS), the human leukocyte antigen (HLA) gene polymorphisms rs3077 and rs9277535 were identified to be associated with chronic hepatitis B. HLA genes have been linked to immune response to infectious agents. Genetic variants in HLA genes influence HLA mRNA expression which might also affect antigen presentation. We evaluated the association between HLA gene polymorphisms and the risk for persistent HBV infection.

METHODS

In the current study, HLA gene polymorphisms were investigated in a case-control study of 294 chronic HBV patients and 234 persons with HBV natural clearance by using a real-time polymerase chain reaction (RT-PCR).

RESULTS

The results showed that rs9277535 allele frequency is associated with HBV infection in the Turkish subjects examined (P=0.048). However, no association was found for rs3077. Additionally, the AG haplotype block showed a protective effect against the risk of persistent HBV infection (for the rs3077A/rs9277535G, OR=0.52; 95% 0.34-0.80, P=0.003).

CONCLUSIONS

Our results, for the first time, demonstrate that HLA-DPB1 gene rs9277535A allele has a major effect on the risk of persistent HBV infection. We suggest that further independent studies are necessary to clarify the association of these polymorphisms with persistence or natural clearance of HBV infection in Caucasian populations.

Understanding the obstacle of incompatibility at residue 156 within HLA-B*35 subtypes

Defining permissive and non-permissive mismatches for transplantation is a demanding challenge. Single mismatches at amino acid (AA) position 156 of human leucocyte antigen (HLA) class I have been described to alter the peptide motif, repertoire, or mode of peptide loading through differential interaction with the peptide-loading complex. Hence, a single mismatch can tip the balance and trigger an immunological reaction. HLA-B*35 subtypes have been described to evade the loading complex, 156 mismatch distinguishing B*35:01 and B*35:08 changes the binding groove sufficiently to alter the sequence features of the selected peptide repertoire. To understand the functional influences of residue 156 in B*35 variants, we analyzed the peptide binding profiles of HLA-B*35:01^156Leu, B*35:08^156Arg and B*35:62^156Trp. The glycoprotein tapasin represents a target for immune evasions and functions within the multimeric peptide-loading complex to stabilize empty class I molecules and promote acquisition of high-affinity peptides. All three B*35 subtypes showed a tapasin-independent mode of peptide acquisition. HLA-B*35-restricted peptides of low- and high-binding affinities were recovered in the presence and absence of tapasin and subsequently sequenced utilizing mass spectrometry. The peptides derived from B*35 variants differ substantially in their features dependent on their mode of recruitment; all peptides were preferentially anchored by Pro at p2 and Tyr, Phe, Leu, or Lys at pΩ. However, the Trp at residue 156 altered the p2 motif to an Ala and restricted the pΩ to a Trp. Our results highlight the importance of understanding the impact of key micropolymorphism and how a single AA mismatch orchestrates the neighboring AAs.

The frequency of HLA alleles in the Romanian population

Knowledge of human leukocyte antigen (HLA) allele frequencies is essential for bone marrow and kidney donor searches. The Romanian Caucasian population is heterogeneous and information on HLA polymorphism has not been well studied. We characterized the HLA genetic profile and allele frequencies of regional populations in Romania. HLA-A, B and DRB1 alleles were examined in 8252 individuals, belonging to the four main regions of Romania. The most common alleles found in the Romanian population are the following: HLA-A*01, A*02, A*03, A*11, A*24; HLA-B*18, B*35, B*44, B*51 and HLA-DRB1*01, DRB1*03, DRB1*07, DRB1*11, DRB1*13, DRB1*15, DRB1*16. More than half of the alleles are non-homogeneously spread in Romania. These results provide a starting point for future analyses of genetic heterogeneity in Romania.

Polymorphisms of HLA-A, -B, -Cw and DRB1 antigens in Moroccan patients with ankylosing spondylitis and a comparison of clinical features with frequencies of HLA-B*27

Ankylosing spondylitis (AS) is very often associated with human leukocyte antigen (HLA), particularly HLA-B*27. However, the strength of this association and clinical features may vary in different ethnic groups. Our study aims to assess the distribution of HLA-A, -B, -Cw and DRB1 alleles in Moroccan patients with AS and to compare the clinical features of AS and the frequencies of HLA-B27 in patients from Morocco with other series. Seventy-five patients diagnosed with AS and assessed for clinical manifestations were selected and compared to 100 healthy controls. HLA class I and II antigens were typed by polymerase chain reaction sequence-specific oligonucleotide. HLA-B27 subtypes were studied by polymerase chain reaction amplification with sequence-specific primers. HLA-B27 was found in 64% of patients. It was positively associated with younger age at disease onset, family history, and uveitis while it had a negative association with late onset. Six B*27 subtypes were identified in the AS group. HLA-B*2705 and B*2702 were the most common observed subtypes. Among other HLA genes, a significant increase in the prevalence of HLA-Cw*02 and HLA-DRB*15 was found in AS patients. HLA-B27 is involved in the predisposition of AS in the Moroccan population. HLA-B*2705 and B*2702 were the predominant subtypes supporting previous reports in Caucasian spondyloarthropathies. Other HLA genes, HLA-Cw*02 and HLA-DRB1*15, seem to confer predisposing effect to the disease. However, the lower frequency of HLA-B27 compared to the literature in our study suggests the existence of different genetic and/or environmental factors in Morocco.

Moroccan study of HLA (-A, -B, -C, -DR, -DQ) polymorphism in 647 unrelated controls: Updating data

The scope of this study is to investigate the HLA (Human Leukocyte Antigen) distribution and polymorphism in a large sample of healthy Moroccans in order to extend and update the available data. 647 unrelated Moroccan controls originating from diverse regions of the country were typed using microlymphocytotoxicity for HLA-A and -B, sequence-specific-primer amplification for -C, -DR, and -DQ and Luminex HD for specific -DR. The most frequent allele groups detected were HLA-A2 (19.2%), -B44 (12.4%), -C*07 (24.4%), -DRB1*03 (16.9%), -DRB1*04 (18.4%), -DQB1*02 (28.7%) and -DQB1*03 (27.8%). The most predominant specific alleles found for DRB1 were: *03:01, *04:02, *04:05, *07:01, *11:01, *13:02 and *15:01. Rare allelic variants were detected, for the first time in Moroccan population, at the DRB1*03 (*03:52, *03:54, *03:56), DRB1*07 (*07:07, *07:11, *07:16) and DRB1*11 (*11:70) locus. The most frequent haplotypes were: A2-B44, A30-B18, A2-C*16, A30-C*06, B14-C*08, B58-C*07, B45-C*06, DRB1*03-DQB1*02, DRB1*04-DQB1*03, DRB1*07-DQB1*02 and DRB1*15-DQB1*06. Comparison of genetic distances and haplotypes with other populations shows that the Moroccans are genetically closer to North Africans and Europeans than to sub-Saharan Africans. Our results reflect the high degree of HLA polymorphism in the Moroccan population and provide a useful baseline of healthy Moroccan controls for disease association and anthropological studies.