The Dai minority population of Southwest China: Heterogeneity of DR2-Associated HLA-DRB1,DRB5, DQA1, and DQB1 haplotypes

HLA-DR2 is the most common DR specificity (60.3%) identified in the Dai minority population of Xishuangbanna, Yunna Province, China. We characterized the DRB1, DRB5, DQA1, and DQB1 alleles of 44 unrelated DR2-positive individuals, 11 of whom (15%) were DR2 homozygous. Four DRB1 and four DRB5 alleles encoding DR2 were identified in this population. The most frequent DR2-associated DRB1 alleles were *1602 (gf = 0.164) and *1502 (gf = 0.151). DRB1*1501 (gf = 0.048) and a new allele designated DRB1*1504 (gf = 0.014) were also detected, but *1601 and *1503 were absent. The most frequent DR2-associated DRB5 alleles were *0101 (gf = 0.233) and *0102 (gf = 0.110). Nine different DR2-associated DR/DQ haplotypes were identified. The two most common DR2 haplotypes were DRB1*1602,DRB5*0101,DQA1*0102,DQB1*0502(hf = 0.142) and DRB1*1502,DRB5*0102,DQA1*0101, DQB1*0501 (hf = 0.075). The new DRB1*1504 allele was found on a single haplotype: DRB1*1504, DRB5*0101,DQA1*0102,DQB1*0502 (hf = 0.017). The Dw2, Dw12, Dw21, and Dw22 haplotypes, present in many other Asian and Mongoloid populations, were not identified in this unique group. However, the Dai minority population is characterized by a relatively large number of diverse DR2 haplotypes and a new DRB1 allele encoding DR2.     

HLA-DR2 HAPLOTYPIC DIVERSITY IN POPULATIONS OF SOUTH-EAST ASIA,NORTHERN CHINA,MELANESIA AND AUSTRALIAN ABORIGINES USING PCR-RFLP FOR DRB1, DRB5, DQA1 AND DQB1. A NOVEL DRB1 ALLELE: DRB1 * 16022

The polymorphism of the human leucocyte antigen HLA-DR2 and the heterogeneity of HLA-DR2 class II-related haplotypes (HLA-DRB1-DRB5-DQA1-DQB1) were investigated in four populations of east and south-east Asia (SEA) and five Melanesian populations using TaqI restriction fragment length polymorphism (RFLP) analysis, and the polymerase chain reaction (PCR) amplification-based techniques PCR-RFLP and sequence-specific oligonucleotide (SSO) typing. The haplotype DRB1*1502-DRB5*0101-DQA1*0102-DQB1*0601 was common in Malaysians, Javanese, Thursday Islanders, Madang, Goroka and the Australian Aborigines, while DRB1*16021-DRB5*0101-DQA1*0102-DQB1*0502 was common in the Thai and Thursday Islanders. DRB1*1501-DRB5*0101-DQA1*0102-DQB1*0602 was present at a high frequency in Northern Chinese, Goroka, Watut and Australian Aborigines. The study describes four rare or unusual haplotypes: HLA-DRB1*1501-DRB5*0101-DQA1*0101-DQB1*0601, DRB1*1502-DRB5*0101-DQA1*0101-DQB1*0502, DRB1*1502-DRB5*0102-DQA1*0102-DQB1*0502 and DRB1*1501-DRB5*0101-DQA1*0101/2-DQB1*0503; the latter two were confirmed by segregation in two Javanese families. A new DR2 allele, initially detected by PCR-RFLP and confirmed by DNA sequencing as DRB1 * 16022 (previously designated DRB1 * 16Madang), was seen in a Madang individual. A new HLA-DR2 TaqI RFLP subtype, locally designated as DR15U, is also described. This RFLP subtype segregated in a Javanese family and correlated with a typically SEA haplotype, DRB1*1502-DRB5*0102-DQA1*0101-DQB1*0501. The allele HLA-DR16Thai, determined by TaqI DRB RFLP, was found by PCR-RFLP and SSO typing to correlate with a unique SEA haplotype, HLA-DRB1*16021-DRB5*0101-DQA1*0102-DQB1*0502, and was observed in the Thai, Malaysian, Thursday Islander, Javanese and Northern Chinese populations.     

Novel HLA-DR2 and -DR3 haplotypes among Norwegian Caucasians

In the Northern European population, all DR2 haplotypes encoded by DRB1*1501 have previously been found to carry the DQA1*0102 and DQB1*0602 alleles, and DR3 haplotypes have been found to carry the DQA1*0501 and DQB1*0201 alleles. Here we report a novel recombinant DR2 haplotype carrying the DRB1*1501, DQA1*0102 and DQB1*0603 alleles as well as a novel recombinant DR3 haplotype carrying the DRB1*0301, DRB3*0101, DQA1*0102 and DQB1*0602 alleles.     

HLA-DR, -DQA1 and -DQB1 associations in Australian multiple sclerosis patients

Molecular genotyping for the major histocompatibility complex (MHC) class II loci, HLA-DRB1, -DQB1 and -DQA1, in 100 patients with relapsing/remitting multiple scerlosis (MS) demonstrated an association with the HLA-DR2, DQw6-associated alleles DRB1*1501, DQB1*0602 and DQA1*0102, thereby extending this finding among MS patients in several countries to an Australian population. Analysis by the relative pre-dispositional effect (RPE) method provided no evidence for a second susceptibility allele at either DQA1 or DQB1. However, our data and that of others suggest a negative association with DQA1*0101. Associations were found with DQB1 alleles sharing sequence homology with DQB1*0602, with DQB1 alleles encoding leucine at residue 26 (Leu 26), with DQA1 alleles encoding glutamine at residue 34 (Gln 34) and with Leu 26 plus Gln 34 alleles, but each was shown by two-loci linkage analysis to be secondary to the DRB1*1501, DQB1*0602, DQA1*0102 association. The recently reported negative association with DQA1 alleles encoding phenylalanine at amino acid 25, leucine at amino acid 69 and arginine at amino acid 52 was not found in this study, although there was a trend towards reduced phenylalanine at amino acid 25. The determination at a molecular level of an explanation for the world-wide association with these alleles remains elusive despite major advances in MHC typing.     

Analysis of HLA-DR2-associated polymorphisms by oligonucleotide hybridization in an Asian Indian population

Among major histocompatibility complex class II antigens, HLA-DR2 appears to have a much larger degree of polymorphism than usually recognized by routine serology or restriction fragment length polymorphisms. We have utilized oligonucleotide probes to further identify the DR2 specificity and its molecular subtypes on the basis of specific DNA sequences as they occur in a select sample from the Asian Indian population. In addition, oglinucleotide typing of HLA-DQA1 and -DQB1 genes allowed us to determine specific associations of DRB1, DRB5, DQA1, and DQB1 alleles in DR2 individuals. A set of 60 oligonucleotide probes were hybridized to polymerase chain reaction (PCR)-amplified DNA from DR2 homozygous or heterozygous individuals. The most common DR2 subtypes that occured in this selected population are: DRB1^*1501 (60%), DRB1^*1502 (33.8%), and DRB1^*1602 (6.2%). No example of DRB1^*1601 was detected. By combining these results with the allelic variations at DQA1 and DQB1, we were able to detect at least seven different haplotypes, the most common being DRB1^*1502-DRB5^*0102- DQA1^*0103-DQBI^*0601 and DRBI^*1501-DRB5^*0101 DQA1^*0102-DQB1^*0502. At least five unexpected combinations, not reported among Western Caucasians, were noticed in this sample. Thus oligonucleotide typing is a valuable tool for defining further polymorphisms in the HLA-D region as exemplified by its applications to typing DR2-positive patients with tubercoloid leprosy and pulmonary tubercolosis.     

Polymorphism and distribution of HLA-DR2 alleles and haplotypes in a Greek population

Abstract: HLA-DR2 serological subtyping has indicated that the DR16 serotype appears at a higher frequency relative to the DR15 serotype in the Greek population, differing from the distribution observed in most other Caucasian groups. In this study, we have analyzed by the PCR-SSP technique a DR2-positive group of unrelated Greek individuals selected from our normal control panel for the different DRB1, DRB5, DQB1 and DQA1 DR2-associated alleles present. Six of the 50 individuals analyzed were homo-zygous for DR2, contributing a total of 56 haplotypes for DR2. The observed frequencies of the DR2-related DRB1 alleles were as follows: 58.9% for the DRB1*1601, 7.1% for the DRB1*1602, 25.0% for the DRBl*1501 and 7.1% for the DRB1*1502 allele. The rare allele DRB1*1605 was detected in one heterozygous sample and its presence was definitively established by DNA sequencing. The alleles *1503, *1504, *1505, *1603 and *1604 were not detected. Three DRB5 alleles were identified: DRB5*0202 (67.8%), DRB5*0101 (25.0%) and DRB5*0102 (7.1%). Ten different DRB1/DQB1/ DQA1 DR2-associated haplotypes were denned. The most frequently observed haplotype was DRBl*1601-DQBl*0502-DQAl*0102 (relative frequency =57%) followed by DRB1*1501-DQB1*0602-DQA1*0102 (relative fre-quency=14.3%). In conclusion, the refined analysis of the DR2-associated DRB1 alleles in the Greek population revealed the prevalence of the DRB1*1601 allele. The rare allele DRB1*1605 was demonstrated once. A considerable variety of different DR2-related DR/DQ haplotypes was detected and the overall haplotypic frequencies in the Greek population are distributed differently compared to those reported for most other Caucasian populations.     

西双版纳傣族及上海汉族群体HLA－DR2相关的DR／DQ单倍型分析

对４４名西双版纳傣族和９名上海地区汉族ＤＫ２阳性个体进行了与其相关的ＤＲ／ＤＱ单倍型组合的分析。傣族群体中ＤＲＢＩ－ＤＲ２亚型分布以＊１６０２与＊１５０２为最常见，其等位基因频率分别为４３．６％与，４０．０％和汉族群体中以＊１５０１为主明显不同。傣族群体中共检出１０种与ＤＲ２相关联的ＤＲ／ＤＱ单倍型；最常见的是ＤＲＢ１＊１６０２、ＤＲＢ５＊０１０１、ＤＱＡ１＊０１０２、ＤＱＢ１＊０５０２（３４．５％）与汉族及其他群体明显不同，本研究表明傣族不仅具有高频率的ＤＲ２，而且与ＤＲ２相关联的ＤＲＢ１、ＤＲＢ５、ＤＱＡ１、ＤＱＢ１单倍型组合有其独特性。     

HLA class II (DRB1, DQA1 and DQB1) allele and haplotype frequencies among HIV-infection discordant Thai couples

We investigated the association of HLA-DRB1, -DQA1 and -DQB1 alleles and haplotypes in 33 Thai HIV discordant couples. A significantly lower frequencies of DRB1*14 (3.0% vs 11.3%, p = 0.048) and DQA1*0103 (0.0% vs 5.63%, p = 0.042) alleles were found in the seropositive individuals when compared with HIV-negative controls. In contrast, there was no significant difference in HLA-DQB1* allele frequencies. The haplotype analysis revealed that DRB1*1501-DQA1*0102-DQB1*0601 (7.6% vs 0.0%, p = 0.002), DRB1*0405-DQA1*0302-DQB1*0401 (7.6% vs 1.3%, p = 0.024) and DRB1*1401-DQA1*0104-DQB1*05031 (6.1% vs 0.0%, p = 0.007) were found to be significantly higher frequencies when compared between HIV seronegative partners and HIV negative controls, but DRB1*1501-DQA1*0102-DQB1*0502 (0.0% vs 8.1%, p = 0.01) was significantly lower. The DRB1*1602-DQA1*0101-DQB1*0502 (4.6% vs 0.0%, p = 0.024) haplotype was found to be significantly higher frequencies in HIV seropositive individuals when compared to HIV negative controls but the DRB1*1502-DQA1*0101-DQB1*0501 (1.5% vs 8.1%, p = 0.049) haplotype was lower.     

HLA class II allele and haplotype frequencies in Koreans based on 107 families

We have investigated the distribution of HLA class II alleles and haplotypes in 107 Korean families (207 parents and 291 children) for the HLA-DRB1, DRB3/B4/B5, DQA1, DQB1 and DPB1 loci. Numbers of alleles observed for each locus were DRB1: 25, DQA1: 14, DQB1: 15, and DPB1: 13. Only two to three alleles were observed for the DRB3 (*0101, *0202, *0301), DRB4 (*0103, * 0103102 N), and DRB5 (*0101, *0102) loci. These alleles showed strong associations with DRB1 alleles: DRB3*0101 with DRB1*1201, *1301 and *1403; DRB3*0301 with DRB1*1202 and *1302; DRB3*0202 with DRB1*0301, *1101, *1401 and *1405; DRB5*0101 and *0102 were exclusively associated with DRB1*1501 and *1502, respectively. The seven most common DRB1-DQB1 haplotypes of frequencies > 0.06 accounted for 52% of the total haplotypes. These haplotypes were exclusively related with the seven most common DRB1-DRB3/B4/B5-DQA1-DQB1 haplotypes: DRB1*1501-DRB5*0101-DQA1*0102-DQB1*0602 (0.085), DRB1*0405-DRB4*0103-DQA1*0303-DQB1*0401 (0.082), DRB1*09012-DRB4*0103-DQA1*0302-DQB1*03032 (0.082), DRB1*0101-DQA1*0101-DQB1*0501 (0.075), DRB1*0701-DRB4*0103-DQA1*0201-DQB1*0202 (0.065), DRB1*0803-DQA1*0103-DQB1*0601 (0.065), and DRB1*1302-DRB3*0301-DQA1*0102-DQB1*0604 (0.065). When these haplotypes were extended to the DPB1 locus, much diversification of haplotypes was observed and only one haplotype remained with a frequency of > 0.06: DRB1*0405-DRB4*0103-DQA1*0303-DQB1*0401-DPB1*0501 (0.062). Such diversification would have resulted from cumulated events of recombination within the HLA class II region, and the actual recombination rate observed between the HLA-DQB1 and DPB1 loci was 2.3% (10/438 informative meioses, including 2 recombinants informative by analysis of TAP genes). Comparison of the distribution of DRB1-DQB1 haplotypes with other populations revealed that Koreans are closest to Japanese people. However, Koreans share a few haplotypes with white people and Africans, which are rare in Japanese: DRB1*0701-DQB1*0202 and DRB1*1302-DQB1*0609. The results obtained in this study will provide useful information for anthropology, organ transplantation and disease association studies.     

中国南方汉族人群HLA—DQB1基因对系统红斑狼疮的易感性研究

应用ＰＣＲ－ＲＦＬＰ核苷酸分型方法，探讨了我国南方浙江沪汉族人群ＨＬＡ－ＤＱＢ１基因多态性与系统红斑狼疮（ＳＬＥ）的遗传关联性，对４８例ＳＬＥ患者的血样分析表明，ＳＬＥ患者具有显著高的ＤＱＢ１＊０６０１等位基因频率（３０．２１％，ＲＲ＝２．８９１９，Ｐｃａｒｒ＝０．０１１２，ＥＦ＝０．２０），ＤＱＢ１＊０６０１可能是一易感基因，而ＤＱＢ１＊０３０１（２．０８％，ＲＲ＝０．１１０８，Ｐｃｏｒｒ＝０，     

Molecular characterization of a recombinant HLA-DR1/DR2 haplotype

Serologic analysis of two families identified an HLA-DR haplotype in which DR1 and DR2 cosegregated. DNA-RFLP analysis of these families with an HLA-DRB probe revealed a pattern of hybridization suggestive of a recombination between DR1 and DR15. Following amplification, cloning, and nucleotide sequencing of HLA-DRB-gene second-exon DNA sequences, three DRB amplification products associated with the novel haplotype were identified: these corresponded to DRB1*0101, DR2 pseudogene, and DRB5*0101. Clones representing the DRB1*1501 and DR1 pseudogenes were not identified: oligonucleotide typing with DRB1*1501-specific probes confirmed the absence of this gene within the DR1/DR2 haplotype. We postulate that the DR1/DR2 haplotype represents a recombinant between those of DR1-Dw1 and DR15-Dw2, and that the crossing-over may have been between the DRB1*0101 gene and the DR2 pseudogene. This is further supported by DNA-RFLP analysis with HLA-DQB and DQA CDNA probes, which revealed conserved linkage genes between the DQB1*0501, DQA1*0101, and DRB1*0101 genes.     

HLA—DR,DQ基因多态性与系统性红斑狼疮相关性的研究

应用聚合酶链反应结合顺序特异的寡核苷酸探针杂交（ＰＣＲ／ＳＳＯＰＨ）方法对江苏籍汉族ＳＬＥ患者和健康对照组ＨＬＡ－ＤＲＢ１、ＤＱＡ１：ＤＱＢ１基因作寡核苷酸分型。结果发现患者组中ＤＲＢ１＊１５０１、ＤＱＡ１＊０１０２等位基因频率及ＨＬＡ－ＤＲＢ１＊１５０１、－ＤＱＡ１＊０１０２、－ＤＱＢ１＊０６０２单倍型频率均明显高于正常对照组；相反，ＤＲＢ１＊０４（ＤＲ４）、ＤＱＡ１＊０６０１频率则明显低于正常对照组。所有ＤＱＢ１等位基因频率在两组间无显著差异，而ＤＱＡ１＊０１０２仅存在于ＤＲ２阳性的个体之中，推测汉族ＳＬＥ的易感基因可能靠近ＤＲ位点，且与单倍型ＨＬＡ－ＤＲＢ１＊１５０１、－ＤＱＡ１＊０１０２、－ＤＱＢ１＊０６０２紧密连锁，该单倍型可作为汉族ＳＬＥ易感的遗传标记。相反ＤＲ４，ＤＱＡ１＊０６０１则对ＳＬＥ发病可能有一定的保护性。     

Functional categorization of HLA-DRB1 alleles in rheumatoid arthritis: the protective effect

Because of past recombination event, human leukocyte antigen (HLA) alleles that are not closely related in overall sequence may come to resemble each other in areas coding for peptide binding regions (PBR) of HLA molecules. Peptide binding is likely to be important for the role of HLA molecules in autoimmune disease. As a result, it has been suggested that a strategy of searching for HLA disease associations that groups alleles in functional categories based on PBR motifs may be more successful than conventional strategies based on studying different alleles. Using such functional categorization, we examined the possibility of discriminating subcategories of HLA-DRB1 alleles associated with rheumatoid arthritis (RA) in a Southern French population. HLA-DRB1 genotyping was performed by polymerase chain reaction with sequence-specific oligonucleotide hybridization or sequence-specific primers. HLA-DRB1 alleles were classified according to a functional categorization that defined seven similar subregion structures or restrictive supertype patterns (RSPs) within pocket 4 of HLA-DR peptide binding groove as the molecular basis for grouping these alleles. HLA-DRB1* RSPs "A," "De," "Q," "Dr," "E," " R," and "a" association with susceptibility or resistance to disease was then studied in 200 RA patients versus 200 controls. DRB1* RSP "A" containing the shared epitope alleles (DRB1*0101, *0102, *0401, *0404, *0405, *0408, *1001, *1402; odds ratio [OR] = 4.35; pc < 0.001) had a predisposing effect, with double-dose effect as expected, OR 6.68 (pc < 0.001). Among the six remaining RSPs, two had significantly protective effect: DRB1* RSP "De" (DRB1*0103, *0402, *1102, *1103, *1301, *1302, *1304; OR = 0.33; p(c) < 0.001), and DRB1* RSP "Q" (DRB1*0701; OR = 0.40; pc < 0.001). One had non-significantly protective effect: DRB1* RSP "Dr" (DRB1*08, *1101, *1104, *1106, *12, *1303, *16; OR = 0.68; p < 0.05, pc = not significant [NS]). Three had neutral effect: HLA-DRB1* RSPs "E" (DRB1*0403, *0407, *0901, *1401; OR = 0.71; p = NS), " R" (DRB1*0301, *0302; OR = 0.76; p = NS), and "a" (DRB1*1501, *1502; OR = 0.94; p = NS). The functional categorization allowed us to discriminate among the HLA-DRB1 alleles those that confer a predisposing effect, a neutral effect, and a protective effect in RA.     

Molecular analysis of HLA class II polymorphism in Croatians

Abstract: HLA-class II polymorphisms have been studied in a population of 141 unrelated healthy Croatians using PCR amplification, followed by non-radioactive oligonucleotide hybridization. Thirty one DRB1, 8 DQA1, 13 DQB1 and 16 DPB1 alleles were found in the tested population. DRB1*1601, 0701, 1501, 0101 and 1104 are the most frequent alleles at the DRB1 locus. At the DQA1 locus two alleles predominate: DQA1*0501 and 0102, while the most frequent DQB1 allele is *0301. Analysis of HLA-DPB1 polymorphism showed that, as in other Europeans, DPB1* 0401 is the most frequent allele. Four different two locus haplotypic associations (DRB1-DRB3, DRB1-DRB5, DRB1-DQB1 and DQA1-DQB1) as well as three locus DRB1-DQA1-DQB1 haplotypic associations were assigned on the basis of known linkage disequilibria. Several unusual two-locus associations have been observed: DRB1*0301-DRB3* 0202, DRB1*1501-DRB5*02, DRB1*1601-DRB5*0101, DRB1*1502-DRB5*0101, DQA1*0103-DQB1*0503 and DQA1*0501-DQB1*0302. Among 236 examined DRB1-DQA1-DQB1 haplotypic combinations, the most frequent was DRB1*1601-DQA1*0102-DQB1*0502 that was found with statistically significant higher frequency than in other Europeans. Twenty-eight distinct probable haplotypes were observed just once, suggesting that the main characteristic of Croatian population is great heterogeneity of haplotypes. This study will serve as a reference for further anthropology studies, HLA and disease associations studies and for donor/recipient matching in organ and bone marrow transplantation.     

HLA-DR,DQ nucleotide sequence polymorphisms in five Melanesian populations

HLA-DRB1 nucleotide sequence polymorphisms have been examined in 304 Melanesians from the Papua New Guinean coast (Madang), islands (Rabaul) and highlands (Goroka), and from New Caledonia and Fiji. A total of 20 HLA-DRB1 alleles were detected by oligonucleotide hybridizations of exon 2 HLA-DRB1 polymerase chain reaction products, in a typing protocol designed to detect all 42 officially-designated HLA-DRB1 alleles. DRB1*1502 and 1101 alleles were the most common alleles in coastal and island Melanesians, while DRB1*1501, 1502 and 1408 predominated in Papua New Guinean highlanders. Undefined mixed lymphocyte reaction determinants in earlier studies of Melanesians could be accounted for in the present study as DRB1*0410, 1407 and 1408 in Papua New Guinean highlanders and as DRB1*1104 and 1602 in coastal people. Nucleotide sequence polymorphisms at HLA-DQA1, -DQB1, -DRB3 and -DRB5 were also determined for estimating HLA-DR,DQ allelic disequilibrium relationships; unusual haplotypes in Melanesians included DBR1*1502, DRB5*0101 and DRB1*0410, DQB1*0402. Previous claims of limited heterogeneity in the HLA-DR allele repertoire in Melanesians are now seen to reflect limitations of early typing reagents rather than any dramatic restriction in HLA-DR allelic diversity.     

MHC class II alleles and haplotypes in patients with pemphigus vulgaris from India

Pemphigus vulgaris (PV) is a blistering disease of the skin and mucous membranes characterized by an autoantibody response against a keratinocyte adhesion molecule, desmoglein 3, causing acantholysis and blister formation. We compared high resolution MHC class II alleles and haplotype frequencies (HLA-DRB, DQA1 and DQB1) in 37 patients with PV to 89 haplotypes of normal relatives from New Delhi and Ahmedabad. We found that PV patients had significantly increased frequencies of DRB1*1404 (P<0.0001), DQA1*0101 (P=0.001), and DQB1*0503 (P<0.0001). These associations were due to the increased frequencies of the haplotype HLA-DRB 1 * 1404, DRB3*0202, DQA1*0101, DQB1*0503 in patients compared to control haplotypes (p<0.0001). Also, patients from Ahmedabad had a significant increase in HLA-DQB 1*0302 (p=0.03). An identical amino acid sequence (Leu-Leu-Glu-Arg-Arg-Arg-Ala-Glu), in positions 67–74 of the P domain of DRB alleles is restricted to some DR14 alleles. Therefore, there are three possible explanations for class II allele involvement in autoantibody in PV patients with class II haplotypes marked by HLA-DR14. First, the class II alleles could be markers for an unidentified susceptibility gene in linkage disequilibrium with them. Second, the primary association could be with DQB 1*0503 and the association with HLA-DR14 alleles would be the result of linkage disequilibrium. Third, the HLA-DRB 1 locus susceptibility could involve a specific amino acid sequence in the third hypervariable region shared by several HLA-DR14 alleles.     

The HLA-DRA*0102 allele: correct nucleotide sequence and associated HLA haplotypes

Here we correct the nucleotide sequence of a single known variant of the HLA-DRA gene. We show that the coding regions of the HLA-DRA*0101 and HLA-DRA*0102 alleles do not differ at two codons as reported previously, but only in codon 217. Using nucleotide sequencing and DNA samples from individuals homozygous in the major histocompatibility complex, we found that the variant, leucine 217-encoding HLA-DRA*0102 allele was present on the haplotypes HLA-B*0801, DRB1*03011, DQB1*0201 (ancestral haplotype AH8.1), HLA-B*07021, DRB1*15011, DQB1*0602 (AH7.1), HLA-B*1501, DRB1*15011, DQB1*0602, HLA-B*1501, DRB1*1402, DQB1*03011 and HLA-A3, B*07021, DRB1*1301, DQB1*0603. The HLA-DRA*0101 allele coding for valine 217 was observed on the haplotypes HLA-B*5701, DRB1*0701, DQB1*03032 (AH57.1), HLA-DRB1*04011, DQB1*0302, HLA-DRB1*0701, DQB1*0202, and HLA-DRB1*0101, DQB1*05011.     

Increasing complexity of HLA-DR2 as detected by serology and oligonucleotide typing.

Serological and oligonucleotide typing was performed on a number of HLA-DR2-positive cells from different ethnic origin, including DR2 haplotypes with various DQ associations. Exons 2 of DRB1 and DRB5 of DR2-positive individuals were locus-specific amplified and hybridized with a number of different oligonucleotides capable of discriminating between the various Dw2, Dw12, Dw21, and Dw22 associated sequences. The linkage of DRB with DQA1 and DQB1 in these haplotypes was analyzed. Among the DR2- positive cells we could define 10 different DR DQ haplotypes by serology and 13 by oligonucleotide typing. The DR2.ES specificity is a serological DRw15 variant which could not be discriminated by oligonucleotide typing from a DRw15 DQw5 haplotype. The DR2.JA variant represents a unique DRB1*1602 DRB5*0101 haplotype. The DR1+2s haplotype consists of a DRB1 DQ region from a Dw1 and a DRB5 gene from a Dw2 haplotype. Its short DR2 serum pattern can be explained by the absence of a DR2 DRB1 gene product. DRB5*0101 sequences were found in association with DRB1*1501, *1502, *1602, and *0101 alleles. Since the DRB5 gene is capable of such different associations it is comparable to the DRB3 and DRB4 genes. This may have implications for the definition of the broad DR2 specificity which is predominantly encoded by the DRB5 gene product. New DR2 haplotypes included the following DQ combinations: DQw2-positive DQA1/B1*0301/0201 and DQw6-positive DQA1/B1*0102/0601 and *0102/0603 haplotypes.     

HLA-DRB1, DQA1, DQB1 DNA polymorphism in the Bulgarian population

We describe for the first time the use of PCR based techniques to analyze the MHC class II polymorphism of the Bulgarian population. The present study provides the HLA-DRB, DQB1 allele frequencies in 116 Bulgarian individuals and DQA1 alleles frequencies in 100 subjects. DNA from these individuals was typed for DRB and DQB1 typed by the PCR- Allele Specific Amplification (PCR-ASA) method and DQA1 by PCR followed by hybridization using Sequence Specific Oligonucleotides (PCR-SSO). Allele and haplo-type frequencies and linkage disequilibria are computed by the standard methods used for the XIth International Histocompatibility Workshop. The highest frequencies are 0.159, 0.109 and 0.085 for DRB1*1101, DRB1*1601 and DRB1*1301 respectively. Among the eight DQA1 alleles detected, DQA1*0501 (0.344) is found to be much more frequent than the two most frequent alleles DQA1*0102 (0.225) and DQA1*0101 (0.151). Twelve DQB1 alleles are found and three of them, DQB1*0301 (0.280), DQB1*0502 (0.153) and DQB1*0201 (0.133) showed the highest frequencies. The haplo-type DRB1*1101-DQA1*0501-DQB1*0301 (0.079) predominate clearly, followed by DRB1*1601-DQA1*0102-DDQB1*0502 (0.055) and DRB1*0101-DQA1*0101-DQB1*0501. These results indicate that the Bulgarian population is characterized by features representative of the European anthropological type with a substantial contribution from the Southern Belt of Europe.     

Class II allele and haplotype frequencies in Mexican systemic lupus erythematosus patients: the relevance of considering homologous chromosomes in determining susceptibility

The aim of the present study was to determine the relevant major histocompatibility complex (MHC) class II alleles in the genetic susceptibility to systemic lupus erythematosus (SLE) in Mexican Mestizo patients. We examined the gene and haplotype frequencies of the HLA-DRB1, DQA1 and DQB1 alleles by polymerase chain reaction-sequence-specific oligonucleotide probes in 81 Mexican SLE Mestizo patients and 99 ethnically matched controls. We found a significantly increased frequency of the HLA-DRB1*0301 (p(c) = 0.031, odds ratio = 2.63) allele and significantly decreased frequencies of the DRB1*0802 (p(c) = 0.035) and DRB1*1101 (p(c) = 0.037) alleles in the SLE group. Haplotype analysis showed increased frequencies of DRB1*0301-DQA1*0501-DQB1*0201 (p(c) = 0.017, odds ratio = 2.97), and decreased frequency of DRB1*0802-DQA1*0401-DQB1*0402 (p(c) = 0.034) in SLE patients. The most frequently detected haplotypes in SLE patients showed different haplotypic combinations in the homologous chromosome from those found in controls. Thus, the combinations detected in SLE patients were either not detected in the control group or infrequently found. The results suggest that the DRB1*0301 is the principal class II allele associated with the genetic susceptibility to SLE in Mexican patients and that the presence of a specific haplotype of the homologous chromosome in patients with DRB1*0407-DQA1*03-DQB1*0302 and DRB1*1501-DQA1*0102-DQB1*0602 haplotypes could have an additive effect on the susceptibility to the disease. Finally, the low frequency of the DRB1*0301 and DRB1*1501 alleles in the control population suggests that the genetic admixture between Mexican Indians and Caucasian populations was an event that could have increased the risk of Mexicans to develop SLE.