Human leukocyte antigen class I and class II allele frequencies and HIV-1 infection associations in a Chinese cohort

China has one of the most rapidly spreading HIV-1 epidemics. To develop a vaccine targeted to specific human leukocyte antigen (HLA) epitopes in this population, allele distribution analysis is needed. We performed low-resolution class I and II HLA typing of a cohort of 393 subjects from mainland China using a polymerase chain reaction with sequence-specific primers (PCR-SSPs). We found 10 class I alleles present in more than 10% of the population: HLA-A*02, HLA-A*11, HLA-A*24, HLA-B*13, HLA-B*15, HLA-B*40, HLA-Cw*03, HLA-Cw*07, HLA-Cw*01, and HLA-Cw*06. Several class II alleles were found at high frequency (>or=10%): HLA-DRB3, HLA-DRB4, HLA-DRB5, HLA-DRB1*0701, HLA-DRB1*1501, HLA-DRB1*0401, HLA-DRB1*0901, HLA-DRB1*1201, HLA-DQB1*0601, HLA-DQB1*0301, HLA-DQB1*0201, HLA-DQB1*0501, and HLA-DQB*0303. We also estimated 2- and 3-locus haplotype frequencies. Because this cohort contained 280 HIV-1-seropositive and 113 HIV-1-seronegative individuals, we compared allele and haplotype frequencies between the infected and control groups to explore correlations between HLA antigens and susceptibility/resistance to HIV infection. The HLA-B*14 allele was only found in the HIV-1-seropositive group, and many 2-locus haplotypes were significantly overrepresented in this group: HLA-B*14/Cw*08, HLA-B*51/Cw*14, HLA-A*02/B*13, HLA-A*31/Cw*14, HLA-A*02/Cw*06, and the class II haplotype HLA-DRB1*1301/DQB1*0601. Alleles significantly increased in the HIV-1-seronegative controls were HLA-B*44, HLA-Cw*04, and HLA-DRB1*1402. Overrepresented 2-locus haplotypes in the control group were HLA-B*44/Cw*04, HLA-A*31/Cw*03, HLA-A*03/Cw*07, HLA-A*11/B*13, HLA-A*11/B*38, HLA-A*24/B*52, and HLA-A*11/Cw*01. The 3-locus haplotypes HLA-A*24/Cw*03/B*40 and HLA-A*02/B*15/DRB1*1201 were found to be increased significantly in the control group. These data contribute to the database of allele frequencies and associations with HIV infection in the Chinese population.     

HLA class-I and class-II allele frequencies and two-locus haplotypes in Melanesians of Vanuatu and New Caledonia

HLA class-I and class-II allele frequencies and two-locus haplotypes were examined in 367 unrelated Melanesians living on the islands of Vanuatu and New Caledonia. Diversity at all HLA class-I and class-II loci was relatively limited. In class-I loci, three HLA-A allelic groups (HLA-A*24, HLA-A*34 and HLA-A*11), seven HLA-B alleles or allelic groups (HLA-B*1506, HLA-B*5602, HLA-B*13, HLA-B*5601, HLA-B*4001, HLA-B*4002 and HLA-B*2704) and four HLA-C alleles or allelic groups (HLA-Cw*04, HLA-Cw*01, HLA-Cw*0702 and HLA-Cw*15) constituted more than 90% of the alleles observed. In the class-II loci, four HLA-DRB1 alleles (HLA-DRB1*15, HLA-DRB1*11, HLA-DRB1*04 and HLA-DRB1*16), three HLA-DRB3-5 alleles (HLA-DRB3*02, HLA-DRB4*01 and HLA-DRB5*01/02) and five HLA-DQB1 alleles (HLA-DQB1*0301, HLA-DQB1*04, HLA-DQB1*05, HLA-DQB1*0601 and HLA-DQB1*0602) constituted over 93, 97 and 98% of the alleles observed, respectively. Homozygosity showed significant departures from expected levels for neutrality based on allele frequency (i.e. excess diversity) at the HLA-B, HLA-Cw, HLA-DQB1 and HLA-DRB3/5 loci on some islands. The locus with the strongest departure from neutrality was HLA-DQB1, homozygosity being significantly lower than expected on all islands except New Caledonia. No consistent pattern was demonstrated for any HLA locus in relation to malaria endemicity.     

Use of a neural network to assign serologic specificities to HLA-A, -B and -DRB1 allelic products

A computational method was used to predict the serologic specificities of HLA molecules encoded by the HLA-A, -B, and -DRB1 loci. The polypeptide sequences of a subset of alleles (numbering 149) with well-defined serologic assignments were used to train a neural network to predict broad and split serologic assignments for each HLA allelic product. The resultant neural network assignments were compared with those of a validation set containing the sequences of 74 HLA-A, 175 HLA-B, and 117 HLA-DRB1 alleles that had previous serologic test assignments but were not part of the training set. The network was able to correctly predict at least one of the serologic assignments of the majority of the validation alleles (99% of the HLA-A set, 86% HLA-B, 94% HLA-DRB1). The remainder received either no assignment (1% HLA-A, 13% HLA-B, 5% HLA-DRB1) or a different but closely related assignment (1% HLA-B and -DRB1). Overall, the variation in serologic assignment by the network appeared comparable to the assignments seen among different laboratories using serologic techniques. When used to predict the serologic assignments of 393 HLA alleles without known serologic types, the network was able to predict assignments for most alleles (95% HLA-A, 85% HLA-B, 96% HLA-DRB1). The majority of these assignments were consistent with assignments predicted by sequence homologies with known alleles. The remainder did not receive an assignment and likely represent new combinations of epitopes.     

HLA class-I and HLA class-II phenotypic, gene and haplotypic frequencies in Tunisians by using molecular typing data

The aim of this study is to define a reliable reckoning of gene frequencies and six-locus haplotypic frequencies of HLA-A, HLA-B, HLA-C, HLA-DRB1, HLA-DQA1, HLA-DQB1 and HLA-DPB1 in the Tunisian population. One hundred unrelated random, healthy people originating from various parts of Tunisia were typed for the alleles of the loci mentioned above by using the molecular techniques polymerase chain reaction--hybridization with oligonucleotide probe (PCR-SSO) and sequence specific primers (SSP). The population studied appeared to be in Hardy-Weinberg equilibrium. Allelic frequency distributions were observed at each locus. The most frequent HLA-A alleles were HLA-A*02 (39%) HLA-A*0101 (25%), HLA-A*30 (21%) and HLA-A*2301 (18%). Moreover, HLA-3A*3601, HLA-1A*6601, HLA-1A*3402 and HLA-2A*8001 were found; however, no HLA-A*4301 was detected. For the HLA-B locus, the most common in descending order were HLA-B*44 (22%), HLA-B*5001 (19%), HLA-B*51 (16%) and HLA-B*18 (15%). Among the 28 alleles HLA-Cw detected, HLA-Cw*6 and HLA-Cw*7 were highly predominant with the frequencies of 33 and 30%, respectively. For the HLA class-II loci, HLA-DRB1*0701, HLA-DRB1*11, HLA-DRB1*13 and HLA-DRB1*03 were the most frequent DR alleles. For the HLA-DPB1, HLA-DPB1*0401, HLA-DPB1*0301 and HLA-DPB1*0201 were the most frequent DP alleles. Many haplotypes were in a strong positive-linkage disequilibrium. The most frequent haplotypes for HLA-A, HLA-B, HLA-C and HLA-DRDQ were HLA-A*3301, HLA-B*1402, HLA-Cw*0802, HLA-DRB1*0102, HLA-DQA1*0101 and HLA-DQB1*0501; HLA-A*2402, HLA-B*0801, HLA-Cw*0702, HLA-DRB1*0301, HLA-DQA1*0501 and HLA-DQB1*0201; HLA-A*2902, HLA-B*4403.1, HLA-Cw*1601, HLA-DRB1*0701, HLA-DQA1*0201 and HLA-DQB1*0202; HLA-A*3002, HLA-B*1801, HLA-Cw*0501, HLA-DRB1*0301, HLA-DQA1*0501 and HLA-DQB1*0201, with frequencies between 0.025 and 0.015. These data can be used as control data for HLA disease associations and paternity studies, but they are also important for the evaluation of the probability rate of success in determining the optimal matched donor in unrelated stem transplantation for Tunisian patients or patients of Tunisian origin.     

Polymorphisms of HLA genes in Western Javanese (Indonesia): close affinities to Southeast Asian populations

Identification of human leukocyte antigen (HLA) antigens that are known as the highest polymorphic genes has become a valuable tool for tissue transplantation, platelet transfusion, disease susceptibility or resistance, and forensic and anthropological studies. In the present study, the allele and haplotype frequencies of HLA-A, HLA-B, and HLA-DRB1 were studied in 237 unrelated healthy Western Javanese (Indonesia) by the high-resolution polymerase chain reaction-Luminex method. A total of 18 A, 40 B, and 20 DRB1 alleles were identified. The most frequent HLA-A, -B, and -DRB1 alleles were HLA-A*2407 (21.6%), HLA-B*1502 (11.6%) and HLA-B*1513 (11.2%), and DRB1*1202 (37.8%), respectively. The most frequent two-locus haplotypes were HLA-A*2407-B*3505 (7%) and HLA-B*1513-DRB1*1202 (9.2%), and three-locus haplotypes were HLA-A*3401-B*1521-DRB1*150201 (4.6%), HLA-A*2407-B*3505-DRB1*1202 (4.3%), and HLA-A*330301-B*440302-DRB1*070101 (4.2%). HLA allele and haplotype frequencies in addition to phylogenetic tree and principal component analyses based on the four-digit sequence-level allele frequencies for HLA-A, HLA-B, and HLA-DRB1 showed that Western Javanese (Indonesia) was closest to Southeast Asian populations.     

中国北京男男同性恋艾滋病感染者HLA 分型及与疾病进展分析

目的:分析中国北京男男同性恋艾滋病感染者HLA-A、HLA-B、HLA-C 基因频率以及HLA 基因分型与疾病进展关系。方法:序列特异性引物的PCR 扩增(PCR-sequence specific primer typing,PCR-SSP)对310 名随机中国北京男男同性恋艾滋病感染者HLA-A、HLA-B、HLA-C 基因进行分型,采用HIV Molecular Immunology Database 中HLA Analysis Tools 方法计算等位基因频率。结果:在北京男男同性恋艾滋病感染者队列中,HLA-A*1101(34.52%)基因频率最高,其次为HLA-A*0201(31.94%)、HLA-C*0102(27.10%)以及HLA-A*2402(26.45%)。根据艾滋病感染者1 年内CD4 细胞计数变化来判断感染者是否为快速进展者,结果发现快速进展者134 例,非快速进展者176 例。快速进展者中存在低水平的HLA-B*4403(快速进展者1.12%,非快速进展者为4.27%,P = 0.0276),HLA-B*1511(非快速进展者5.98%,快速进展者2.25%,P =0.0282),HLA-B*5701(非快速进展者2.56%,快速进展者0.37%,P =0.0491)表达,而HLA-C*0304 则在快速进展者中高表达(非快速进展者4.56%,快速进展者8.96%,P =0.0319)。结论:本研究获得了中国北京男男同性恋艾滋病感染者HLA-A、HLA-B、HLA-C 基因的等位基因分布频率数据,并发现HLA-B*4403、HLA-B*1511、HLA-B*5701 与延缓艾滋病疾病进展有关,而HLA-C*0304 则与加速艾滋病疾病进展相关。     

HLA repertoire of 115 UAE nationals infected with SARS-CoV-2

The class I and class II Human Leucocyte Antigens (HLA) are an integral part of the host adaptive immune system against viral infections. The characterization of HLA allele frequency in the population can play an important role in determining whether HLA antigens contribute to viral susceptibility. In this regard, global efforts are currently underway to study possible correlations between HLA alleles with the occurrence and severity of SARS-CoV-2 infection. Specifically, this study examined the possible association between specific HLA alleles and susceptibility to SARS-CoV-2 in a population from the United Arab Emirates (UAE). The frequencies of HLA class I (HLA-A, -B, and -C) and HLA class II alleles (HLA-DRB1 and -DQB1); defined using Next Generation Sequencing (NGS); from 115 UAE nationals with mild, moderate, and severe SARS-CoV-2 infection are presented here. HLA alleles and supertypes were compared between hospitalized and non-hospitalized subjects. Statistical significance was observed between certain HLA alleles and supertypes and the severity of the infection. Specifically, alleles HLA-B*51:01 and HLA-A*26:01 showed a negative association (suggestive of protection), whilst genotypes HLA-A*03:01, HLA-DRB1*15:01, and supertype B44 showed a positive association (suggestive of predisposition) to COVID-19 severity. The results support the potential use of HLA testing to differentiate between patients who require specific clinical management strategies.     

HLA haplotypes and birth weight variation: is your future going to be light or heavy?

Birth weight is known to be a direct indicator of perinatal mortality and a clear predictor of adult pathologies too. It has been correlated with several causes of mortality in adulthood: low birth weight with diabetes, nephropathy and cardiovascular diseases and high birth weight with autoimmune diseases and cancer. In genome-wide studies, an extended human leucocyte antigen ( HLA ) region has been linked to birth weight variation. We focused our attention on the HLA haplotypes marked by HLA-A , HLA-B and HLA-DRB1 polymorphisms in 1206 healthy Caucasian newborns belonging to the Cord Blood Bank of Pavia (Italy) and their mothers, aiming to investigate the association between this restricted HLA region and birth weight variation. In our study, the HLA-B*38;DRB1*13 haplotype showed an ascending trend among centiles addressing to the high foetal weight. The HLA-A*02;B*15 haplotype showed a descending trend among centiles addressing to the low foetal weight. Besides the acknowledged correlation between the HLA-A*02 and HLA-B*15 alleles (as well as low birth weight) and type I diabetes and between the HLA-B*38 and HLA-DRB1*13 alleles (as well as high birth weight) and several autoimmune diseases, we cannot predict if our babies, healthy at birth, will suffer from these pathologies during life. Nevertheless, our data point to the HLA telomeric end for markers linked to the low birth weight and to the HLA centromeric end for markers linked to the high birth weight, thus limiting the region involved in birth weight variation, which still represents a useful predictor of disease risk in adulthood.     

The association of human leucocyte antigen (HLA) alleles with COVID-19 severity: A systematic review and meta-analysis

Due to their pivotal role in orchestrating the immune response, HLA loci were recognized as candidates for genetic association studies related to the severity of COVID-19. Since the findings on the effects of HLA alleles on the outcome of SARS-CoV-2 infection remain inconclusive, we aimed to elucidate the potential involvement of genetic variability within HLA loci in the molecular genetics of COVID-19 by classifying the articles according to different disease severity/outcomes and by conducting a systematic review with meta-analysis. Potentially eligible studies were identified by searching PubMed, Scopus and Web of Science literature databases. A total of 28 studies with 13,073 participants were included in qualitative synthesis, while the results of 19 studies with 10,551 SARS-CoV-2-positive participants were pooled in the meta-analysis. According to the results of quantitative data synthesis, association with COVID-19 severity or with the lethal outcome was determined for the following alleles and allele families: HLA-A*01, HLA-A*03, HLA-A*11, HLA-A*23, HLA-A*31, HLA-A*68, HLA-A*68:02, HLA-B*07:02, HLA-B*14, HLA-B*15, HLA-B*40:02, HLA-B*51:01, HLA-B*53, HLA-B*54, HLA-B*54:01, HLA-C*04, HLA-C*04:01, HLA-C*06, HLA-C*07:02, HLA-DRB1*11, HLA-DRB1*15, HLA-DQB1*03 and HLA-DQB1*06 (assuming either allelic or dominant genetic model). We conclude that alleles of HLA-A, -B, -C, -DRB1 and -DQB1 loci may represent potential biomarkers of COVID-19 severity and/or mortality, which needs to be confirmed in a larger set of studies.     

西藏门巴族人群HLA-A、B和DRB1基因座多态性

目的 分析西藏门巴族HLA-A、B和DRB1 3个基因座的遗传特征，并研究其民族起源。方法应用序列特异性寡核苷酸探针反向斑点杂交技术对西藏自治区门巴族居住区47名门巴族无关个体HLA-A、B和DRB1基因座进行分型。对门巴族和我国其他11个群体(民族)的HLA-DRB1基因频率采用Neighbor-Joining(NJ)方法进行聚类分析。结果 在西藏门巴族人群中HLA-A基因座共检出23个等位基因，其中HLA-A*1101，A*2402，A*02011，A*0206基因最常见；HLA-B基因座共检出39个等位基因，其中HLA-B*3802，B*4001，B*4002，B*51011基因最常见；HLA-DRB1基因座共检出33个等位基因，其中HLA-DRB1*12021，DRB1*0403，DRB1*0701，DRB1*1201基因最常见，频率最高的等位基因分别是HLA-A*1101(0．2128)，HLA-B*3802(0．1064)和HLA-DRB1*12021(0．0851)。结论 西藏门巴族人群HLA基因座具有高度遗传多态性，聚类分析门巴族与西藏藏族遗传关系较近。     

Does a central MHC gene in linkage disequilibrium with HLA-DRB1*0401 affect susceptibility to type 1 diabetes?

Subtypes of HLA-DR4 are associated with susceptibility or protection against type 1 diabetes (T1DM). We addressed whether this reflects linkage disequilibrium with the true susceptibility locus by studying broader MHC haplotypes marked by alleles of HLA-B, IKBL (adjacent to TNFA) and complement C4. The study used a largely Caucasian cohort from Western Australia. HLA-DRB1*0401 and HLA-DRB1*0405 marked susceptibility to T1DM. In Caucasians, DRB1*0401 occurs predominantly in the 44.1 ancestral haplotype (AH; HLA-A2,B44, DRB1*0401,DQB1*0301) and the 62.1AH (HLA-A2,B15(62),DRB1*0401,DQB1*0302). HLA-B15 marked susceptibility and HLA-B44 marked with resistance to T1DM in patients and controls preselected for HLA-DRB1*0401. A gene between TNFA and HLA-B on the 8.1AH (HLA-A1,B8,;DR3,DQ2) modifies the effects of the class II alleles. Here, alleles characteristic of the 62.1AH (C4B3, IKBL+446*T and HLA-A2,B15) were screened in donors preselected for HLA-DRB1*0401. C4B3 was associated with diabetes, consistent with a diabetes gene telomeric of MHC class II. However, increases in carriage of IKBL+446*T and HLA-A2,B15 were marginal, as too few control subjects were available with the diabetogenic alleles. However, with these tools, selection of HLA-DRB1*0401, DQB1*0302 donors who are positive and negative for C4B3 will allow bidirectional mapping of diabetes genes in the central MHC.     

Ninety-six novel HLA class I and II alleles identified in volunteers for the National Marrow Donor Program Registry in 2009

Ninety-six novel human leukocyte antigen (HLA) class I and class II alleles are described from volunteers for the 'Be The Match Registry?': 15 HLA-A alleles, 11 HLA-C alleles, 36 HLA-B alleles and 34 HLA-DRB1 alleles. Sixty-eight (～71%) of the 96 novel alleles are single nucleotide substitution variants when compared with their most homologous allele. Twenty-three of these single nucleotide variants are silent substitutions and one creates a non-expressed allele (B(*) 27:59N). The remaining novel alleles differ from their most similar allele by two to five nucleotide substitutions. One of the novel HLA-A alleles (A(*) 11:52Q) is of questionable expression because of a deletion of codon 11. Three of the novel alleles encode amino acid changes at codons 63 (HLA-C), 88 (HLA-B) and 79 (HLA-DRB1) which have not previously been reported to be polymorphic in these loci. Some of the new alleles encode novel codons and unique amino acid changes at polymorphic positions in the HLA-A (codons 115, 149 and 168), HLA-C (codon 90), HLA-B (codons 23, 44, 70, 120 and 153) and HLA-DRB1 (codon 88) loci.     

原发性肾病综合征与HLA-A、HLA-B、HLA-DRB1基因相关性的研究

目的探讨HLA-A、HLA-B、HLA-DRB1位点基因与山西汉族激素抵抗肾病综合征(SRNS)的相关性。方法用聚合酶链反应序列特异性引物法,对30例SRNS患者(成人22例,儿童8例)和45例正常对照者进行了HLA-A、HLA-B、HLA-DRB1等位基因分型,并分析了A、B、DRB1基因在各组的分布。结果SRNS患者组HLA-B*15、B*44基因频率较正常对照组增高(P<0.05);成人SRNS患者组HLA-DRB1*07、B*44基因频率较正常对照组增高(P<0.05),成人SRNS患者组HLA-DRB1*15基因频率较正常对照组降低(P<0.05);儿童SRNS患者组HLA-DRB1*10基因频率较正常对照组增高(P<0.05)。结论SRNS发病可能与HLA-B*15、B*44基因有关,成人SRNS发病可能与HLA-DRB1*07、B*44基因有关,HLA-DRB1*15对成人SRNS发病可能有保护作用,儿童SRNS发病可能与HLA-DRB1*10基因有关;HLA与SRNS的相关性不仅与人种、国家和地区有关,还可能与发病年龄有关。     

Transmission of class I/II multi-locus MHC haplotypes and multiple sclerosis susceptibility: accounting for linkage disequilibrium

The human major histocompatibility complex (MHC) class II region is associated with genetic susceptibility to multiple sclerosis (MS). Roles for HLA class I loci have been supported in several case-control studies, but this methodology does not consider the known linkage disequilibrium (LD) between class I and II loci. In 1258 individuals from 294 MS families, we analysed class I and II interactions. Using transmission disequilibrium test and haplotype analyses, we found positive associations between MS and several HLA-DRB1*15-HLA-A haplotypes including HLA-DRB1*15-HLA-A*02 (P = 2.41 x 10(-5)) and -HLA-A*03 (P = 8.42 x 10(-6)) and several HLA-DRB1*15-HLA-B haplotypes including HLA-DRB1*15-HLA-B*07 (P = 2.23 x 10(-10)). HLA-DRB1*15 haplotypes divergent for reported HLA-A allelic associations were equally over-transmitted, illustrating no detectable effect of HLA-A or -B alleles in cis on susceptibility. HLA-A and -B alleles on haplotypes not bearing HLA-DRB1*15 were not over-transmitted. Similarly, general over-transmission of HLA-DRB1*15 haplotypes was independent of the HLA-B allele present. Furthermore, HLA-B*07 haplotypes from HLA-DRB1*X-HLA-B*X/HLA-DRB1*X-HLA-B*07 heterozygous parents were transmitted per random expectation giving no indication of HLA-B independence or trans complementation of HLA-DRB1*15 by HLA-DRB1*X-HLA-B*07 haplotypes. These results imply that many reports of class I allelic associations in MS are class II dependent, secondary to LD with class II loci. The lack of independent class I associations suggests that virus-related class I-antigen complexes are not T-cell targets in MS. The inability to replicate confirmed case-control associations highlights the importance of family-based analyses. The frequency of allelic associations not being replicated emphasizes the requirement for constructing multi-locus haplotypes in dissecting associations in regions of tight LD.     

Genetic link among Hani,Bulang and other Southeast Asian populations: evidence from HLA -A, -B, -C, -DRB1 genes and haplotypes distribution

Human leucocyte antigen (HLA) genetic characteristic of different ethnic minorities would be useful for tracing the origin of modern human HLA matching in transplantation and disease associations. In this study, we reported HLA-A, -B, -C and -DRB1 alleles and haplotypes in the Bulang and Hani populations of southwestern China using a high-resolution polymerase chain reaction-Luminex (PCR-Luminex) typing method. A total of nine HLA-A, 22 HLA-B, 13 HLA-C and 18 HLA-DRB1 alleles were identified in the Bulang population, and 11 HLA-A, 25 HLA-B, 14 HLA-C and 19 HLA-DRB1 alleles were in the Hani population. Compared with other populations, the predominant A*1101-B*1502-DRB1*1202 haplotype in the Bulang and Hani populations was also common in Jinuo, Wa, Dai, Maonan and Vietnamese populations. The distribution of HLA genes indicate that Bulang and Hani populations belong to the Southeast Asia group and they have maintained their original genetic characteristics and kept a long genetic distance from other populations owing to founder effects and subsequent geographic isolation. In addition, the close relationship among ethnic groups in Yunnan province and the Thai and Vietnamese populations were confirmed, whereas the Mon-Kmer-speaking populations shared other common HLA alleles and haplotypes compared with other linguistic groups.     

Characterization of 236 novel alleles at the HLA-A, -B, -C, -DRB1, -DQB1 and -DPB1 loci from China Marrow Donor Program

Two hundred and thirty-six novel human leukocyte antigen (HLA) alleles are described from volunteer donors of the China Marrow Donor Program: 71 HLA-A alleles, 79 HLA-B alleles, 43 HLA-C, 16 HLA-DRB1 alleles, 26 HLA-DQB1 and 1 HLA-DPB1. Two hundred and thirteen (90.3%) of the 236 novel alleles are single nucleotide substitution variants when compared with their most homologous allele. Seventy-eight of these single nucleotide variants are silent substitutions. The remaining novel alleles differ from their most similar allele by two to four nucleotide substitutions. Some of the novel alleles encode amino acid changes at positions not previously reported to be polymorphic, such as codons 57, 62, 67, 41 and 52 in HLA-A alleles; codons 133, 156, 201 and 215 in HLA-B alleles; codons 74, 208 and 225 in HLA-C; codons 25, 32 and 72 in HLA-DRB1; codons 20, 39 and 77 in HLA-DQB1.