Highly polymorphic promoter regions of HLA DQA1 and DQB1 genes do not help to further define disease susceptibility in insulin-dependent diabetes mellitus

HLA DQA1, HLA DQB1 genes confer susceptibility to insulin-dependent (type 1) diabetes mellitus (IDDM). Since variants of their upstream regulatory regions are linked to the exons, we investigated their promoter polymorphisms (QAP and QBP) by a combination of PCR-based typing protocols in 136 IDDM patients, 167 controls and 6 families with an IDDM proband to identify possible additional susceptibility markers. Of major interest for IDDM susceptibility are the promoter "splits" of HLA DQA1*0301 (QAP3.1 and QAP3.2) and HLA DQB1*0302 (QBP3.2 and QBP3.3). QAP 3.1 (96% in patients vs 98% in controls) and QBP3.2 (100% vs 99%) were found to be the most frequent promoter variants for HLA DQA1*0301 and DQB1*0302, respectively, whereas QAP3.2 and QBP3.3 were very rare. Furthermore the promoter "splits" were equally distributed on the respective exon alleles in all groups and cosegregated in families as expected. In conclusion, HLA DQ-mediated susceptibility and protection in IDDM is not restricted to the exon but extends to the promoter region without further defining the genetic risk.     

Molecular analysis of HLA-DRB1, DQA1, DQB1, DQ promoter polymorphism and extended class I/class II haplotypes in the Seri Indians from Northwest Mexico

The study of the genetics of the Major Histocompatibility Complex (MHC) in Amerindians is of great value in understanding the origins and migrations of these native groups, as well as the impact of immunogenetics on the epidemiology of diseases affecting these populations. We analyzed, using Polymerase Chain Reaction and Sequence Specific Oligonucleotide Probes (PCR-SSOP), DRB1, DQA1, DQB1 alleles and the promoter regions of DQA1 and DQB1 genes in 31 unrelated and 24 related Seri, a Mexican Indian group, from the state of Sonora (Northwest Mexico). The class II genotypes of this population were found to be in genetic equilibrium. The allele frequency (AF) of the prevalent DRB1 alleles were DRB1*0407 (48.4%), DRB1*0802 (33.9%) and DRB1*1402 (16.1%). The most frequent DQA1 and DQB1 alleles were DQA1*03011 (AF = 50.00%), DQA1*0401 (AF = 33.87%) and DQA1*0501 (AF = 16.13%); DQB1*0302 (AF = 50.00%), DQB1*0402 (33.87%) and DQB1*0301 (16.13%); which were in combination with DRB1*0407, DRB1*0802 and DRB1*1402, respectively. Three QAP and three QBP alleles were present (QAP 3.1, 4.1, 4.2; QBP 3.1, 3.21, 4.1) associated with the typical published DQA1 and DQB1 alleles. Four class II haplotypes were present in family members: DRB1*0407-QAP-3.1-DQA1*03011-QBP-3.21-DQB1*0302; DRB1*0802-QAP-4.2-DQA1*0401-QBP-4.1-DQB1*0402; DRB1*1402-QAP-4.1-DQA1*0501-QBP-3.1-DQB1*0301 and DRB1*0701-QAP-2.1-DQA1*0201-QBP-2.1-DQB1*0201. The family data were used to confirm extended haplotypes. A total of 21 haplotypes were found when A* and B* loci were also considered. The three most frequent combinations included A*0201-B*3501-DRB1*0407, A*3101-B*5101-DRB1*0802, and A*0201-B*40-DRB1*1402.     

DQA1 and DQB1 promoter diversity and linkage disequilibrium with class II haplotypes in Mexican Mestizo population

The upstream sequences in the 5' flanking region of HLA class II genes, regulate their expression and contribute to the development of immunological diseases. We analyzed 105 healthy unrelated Mexican Mestizos for QAP and QBP polymorphism. DNA typing for DRB1, DQA1, DQB1, QAP1 and QBP1 was done using a standardized PCR-SSOP. Although all QAP alleles previously described were found in Mexicans, the distribution differed as compared to other populations. QAP-3.1, 4.1 and 4.2 were the most frequent alleles and were associated with DQA1*03, *0501 and *0402 respectively. The prevalent QBP alleles were 3.21, 3.1 and 4.1 found mainly associated with DQB1*0302, *0301 and *0501. Linkage disequilibria between the promoter and the corresponding DQA1 and DQB1 allele, are in general the same as described by others. A total of 61 different haplotypes were defined, only six of them with a frequency above 4%. The haplotypes DRB1*0407-QAP-3.1-DQA1*03-QBP-3.21-DQB1*0302 (HF = 14.37%) and DRB1*0802-QAP-4.2-DQA1*0401-QBP-4.1-DQB1*0402 (HF = 14.22%), which have an Amerindian ancestry, are the most frequent in Mexicans. Some rare combinations were detected such as DRB1*0405-QAP-1.3-DQA1*0101/4-QBP-5.11/5.12-DQB1*0501 and DRB1*0403-QAP-3.2-DQA1*03-QBP-3.21-DQB1*0302, probably due to ancient recombination events. This knowledge is relevant as a basis to evaluate functional implications and to explore the role of promoter diversity in disease expression.     

Endogenous retroviral long terminal repeats of the HLA-DQ region are associated with susceptibility to insulin-dependent diabetes mellitus

HLA-DQ genes are the main inherited factors predisposing to IDDM. This gene region harbors long terminal repeat (DQ LTR) elements of the human endogenous retrovirus HERV-K, which we analyzed for a possible association with disease. We first investigated whether LTR segregate with DQ alleles in families. Members (n = 110) of 29 families with at least one diabetic child, unrelated patients with IDDM (n = 159), and healthy controls (n = 173) were analyzed. Genomic DNA was amplified for DQ LTR3 by a nested primer approach as well as for DQA1 and DQB1 second exons, to assign DQA1 and DQB1 alleles. DQ LTR segregated in 24 families along with DQ alleles. Of the 29 families, 20 index patients were positive for DQ LTR. The DQ LTR was in all patients on the haplotype carrying the DQA1 ^*0301 and DQB1 ^*0302 alleles. A majority of patients had DQ LTR (62%) compared with controls (38%) (p < 1.3 × 10^{− 5}), even after matching for the high-risk alleles DQA1 ^*0501, DQB1 ^*0201-DQA1 ^*0301, and DQB1 ^*0302 (79% of patients and 48% of controls; p < 0.02). Subtyping for DRB1 ^*04 alleles in all DQB1 ^*0302 ⁺ individuals showed 56% DRB1 ^*0401, DQB1 ^*0302 [LTR⁺ patients vs. 29% controls with the same haplotype (p < 0.002). In conclusion, these data demonstrate the segregation of DQ LTR with DQA1, DQB1 alleles on HLA haplotypes. Furthermore their presence on DRB1 ^*0401-, DQA1 ^*0301-, and DQB1 ^*0302-positive haplotypes suggest that they contribute to DQ-related susceptibility for IDDM. Human Immunology 50, 103–110 (1996)     

Polymorphism in the upstream regulatory region of the DQB1 gene (QBP) and four point (DRB1, QBP, DQA1, DQB1) haplotypes in the Dai minority population in China.

Using polymerase chain reaction and Dig-ddUTP labeled oligonucleotides we have investigated the DNA polymorphism for the DQB1 promoter region (QBP) and we have deduced four point haplotypes in 65 unrelated healthy individuals of the Dai minority population. A total of 8 QBP alleles were detected. The most frequent allele is QBP 5.11 with 87.7% allele frequency followed by QBP 3.21, 3.1, 5.12 with 33.8%, 23.1% and 15.4% allele frequency respectively. Four QBP alleles, 3.22, 3.32, 4.1 and 6.12 were absent in the Dai minority. The linkage disequilibrium of the QBP allele with certain DQB1 alleles was very strong. Complete positive association was found for QBP 2.1-DQB1^*0201, QBP3.1-DQB1^*0301, QBP6.11-DQB1^*0601. A total of 32 different four point haplotypes were deduced. Among them the most common haplotypes were DRB1^*1602, DQA1^*0102, QBP5.11; DQB1^*0502, DRB1^*1602-QBP5.11, DQA1^*0102, DQB1^*0502 (N = 19); DRB1^*09 DQA1^*03, QBP3.21, DQB1^*03032 (N = 5); DRB1^*1401, DQA1^*01, QBP5.11, DQB1^*0502 (N = 12) and DRB1^*1202, DQA1^*0601, QBP3.1, DQB1^*0301 (N = 10). We conclude from these data that a) there is a reduced class II polymorphism in the Dai minority population an b) the relationship between QBP and DQB1 alleles is not different from that observed in other populations.     

QAP and QPB polymorphism in Mexican mestizos and Indians

Although the sequences of the class II promoters are highly conserved, diversity has been found in the URRs of DR and DQ loci. For the promoter region of DQA1, 10 QAP alleles are defined and 12 QBP for DQB1 region; DNA of 46 Mexican Mestizos and 101 Seri Indians was typed for QAP, QBP and class II alleles using the PCR-SSO protocols of the 12th W, as part of the promoter component chaired by E. Albert. PCR-SSP was done to distinguish between QBP6.2 and 6.3. In both groups, all QAP alleles previously described were detected, excepting for 3.2, absent because the associated DQA1^*0302 is also lacking. One unusual haplotype accounting for 16.3% was observed: DRB1 ^*0802-QAP4.2-DQA1^*0401-DQB1^*0402-QBP4.1. QBP3.22 described in Whites, was not present in this haplotype. Neither QBP4.1 that associates with DQB1 ^*0401, or the latter have been found in Mexicans. A recombination possibly occured in the DQB1 region of an ancestral haplotype carrying QBP4.1. In Seri Indians, only 8 haplotypes were detected. Of these, 3 seem to be the ancestral ones: ^*0407-^*03011-3.1-^*0302-3.21; ^*0802-4.2-^*0401-^*0402-4.1; and ^*1402-4.1-^*0501-^*0301-3.1. The frequencies of 43.5%, 36.6% and 13.9% accounting for 94% of the haplotypes, indicate from an evolutionary viewpoint, that these originated from Orientals and probably conferred a great biological advantage. They are also the prevalent haplotypes in Mestizos (60.9%). One unusual QBP4.1 combination was detected in 2 Seris with DRB1^*0407-DQB1^*0302. The functional role of these variants in expression and in development of disease, must be explored.     

Genetic differences in HLA-DQA1* and DQB1* allelic distributions between celiac and control children in Santiago, Chile.

Celiac disease is a permanent gluten intolerance strongly associated with HLA class II antigens. The over presentation of particular HLA alleles and haplotypes has been described in several populations. Different lines of evidence obtained during the last years suggest that a particular HLA-DQ heterodimer, encoded by the DQA1*0501 and DQB1*0201 genes in cis or trans conformation, confers the primary disease susceptibility. We report the HLA class II allelic distribution and DQA1/ DQB1 genotypes in 62 Chilean celiac patients compared with 124 control subjects in Santiago, Chile. We found a pronounced increase of the "susceptible" alleles :DQA1*0501 (0.480 vs 0.169, Pc < 0.0005), DQB1*0302 (0.430 vs 0.242, Pc = 0.002) and DQB1*0201 (0.250 vs 0.125, Pc = 0.037) in celiac patients in comparison with control children. As for "protective" alleles, we detected a high frequency of DQA1*0101 (0.310 vs 0.160, Pc = 0.01), DQA1*0201 (0.105 vs 0.010, Pc < 0.0075) and DQB1*0301 (0.250 vs 0.100, Pc = 0.010) in controls. In relation to risk haplotypes, the main combination observed was the conformation DQ8 (DQB1*0302/DQA1*0301) over DQ2 (DQB1*0201/DQA1*0501). In conclusion, results show that celiac disease in Chilean patients is primarily associated with DQ8 conformation. This is concordant with the high frequency of DR4 alleles (in linkage disequilibrium with DQB1*0302) detected in Amerind groups in Chile, where DQB1*0302 is more frequent than DQB1*0201.     

The frequency of QAP2.1 is increased in psoriasis vulgaris patients

The heritage of psoriasis has a polygenic mode, the most essential antigens being Cw6,DR7,DQA1^*0201 in many ethnic groups. We have found a strong association between the high risk HLA haplotypes carrying DQA1^*0201 and psoriasis. Thus, the aim of this study was to further examine if the flanking promotor genes, URRs of DQ (QAP and QBP) are involved in the susceptibility to this disease. The series consisted of 62 patients and 50 control subjects and the PCR-SSO method was used. The frequency of the promoter gene QAP2.1 was significantly increased in the psoriatics (P_c=1.5×10⁻², RR=4.6) and the frequency of QAP4.1 was decreased in the patients group (P_c=3.9×10⁻²). The psoriasis risk allele DQA1^*0201 was associated always with QAP2.1, except once with QAP3.1.

: The combination of QAP2.1 and DQA1^*0201 is associated to psoriasis. Promotor region could exert its influence by gene expression or functionally through different inducibility by cytokines.     

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.     

用PCR-SSP方法研究广西壮族HLA-DQA1和B1基因多态性

目的　检测广西壮族ＨＬＡＤＱＡ１ ,Ｂ１ 基因的多态性。方法　应用ＰＣＲＳＳＰ 方法对１４０ 名健康、无血缘关系广西壮族人的ＨＬＡＤＱＡ１ 和ＤＱＢ１ 进行基因分型。结果　共检出７ 个ＤＱＡ１ 等位基因和１６ 个ＤＱＢ１ 等位基因。在检出的ＤＱＡ１ 等位基因中,０３０１ 的基因频率最高（３５ ％ ） ,０４０１ 的基因频率最低（１ ．１ ％ ） 。在ＤＱＢ１ 等位基因中,０６０１（２２ ．１ ％ ） ,０３０１（２０ ．７ ％ ） ,０５０１（１３ ．９ ％ ） 最为常见。未检出的等位基因包括ＨＬＡＤＱＡ１ ＊ ０２０１ ,０３０２ ,０６０１ ,ＤＱＢ１ ＊ ０６０３ ,０６０５ 和０６０８ 。结论　广西壮族ＨＬＡＤＱＡ１ ,Ｂ１ 基因的多态性不仅有中华民族的特点,而且也有其独特性。     

Polymorphism of HLA-A, -B, -DRB1, -DQA1 and -DQB1 haplotypes in a Croatian population.

We describe for the first time extended haplotypes in a Croatian population. The present study gives the HLA-A, -B, -DRB1, -DQA1 and -DQB1 allele and haplotype frequencies in 105 families with at least two offspring. All individuals were studied by conventional serology for HLA class I antigens (A and B), while class II alleles (DRB1, DQA1, DQB1) were typed using the PCR-SSOP method. HLA genotyping was performed by segregation in all 105 families. For extended haplotype analysis, 420 independent parental haplotypes were included. Fourteen HLA-A, 18 HLA-B, 28 DRB1, 9 DQA1 and 11 DQB1 alleles were found in the studied population. Most of the DRB1 alleles in our population had an exclusive association with one specific DQA1-DQB1 combination. This strong linkage disequilibrium within the HLA class II region is often extended to the HLA-B locus. A total of 10 HLA-A, -B, -DRB1, -DQA1, -DQB1 haplotypes were observed with a frequency 相似文献   

Molecular analysis of HLA allelic frequencies and haplotypes in Jordanians and comparison with other related populations.

Twenty alleles for the locus human leukocyte antigen (HLA-A) and 46 for the HLA-B locus were detected in Jordanians. This indicates the existence of high polymorphism in this area. The most frequent HLA class I alleles found were A*0201 (0.1344), B*0713 (0.1724), and C*0502 (0.1793). Twenty-six different alleles in the Jordanian population were identified for the DRB1 locus being the DRB1*0704 (0.2552), DRB1*0401 (0.1965), and DRB1*1501 (0.0896) the most frequent. Common DQA1 alleles were DQA1*0201 (0.2690), DQA1*0301 (0.2414), and DQA1*0501 (0.1724). Three-loci haplotype heterogeneity was common: 38 HLA class II haplotypes were identified, of which the most frequently observed was DRB1*0401-DQA1*0301-DQB1*0302 (0.1793). In addition, as expected, 220 different five-loci haplotypes with several unusual allelic combinations were observed, although many of them are pan-European haplotypes. The most frequent five-loci haplotype was the A30-B7-DRB1*03-DQA1*0501-DQB1*0201 (0.0138). It seems that the specific Jordanian haplotypes are the following: the A31-B7-DRB1*04/07-DQA1*0301/0201-DQB1*0302/0202 haplotypes (0.0103) and the A1-B7-DRB1*07-DQA1*0201-DQB1*0202, A2-B7-DRB1*04-DQA1*0301-DQB1*0302, A11-B7-DRB1*07-DQA1*0201-DQB1*0201 haplotypes but at lower frequencies (0.007). A tree analysis of HLA class I and class II alleles were made for several Caucasian populations and individual genetic distances calculated. The haplotype frequencies, genetic distances, and dendrograms do not reveal great differences as compared with those in other Mediterranean countries and Western Europeans populations. Our results suggest that both HLA class I and class II polymorphism (but especially the former) of the Jordanian population demonstrates considerable heterogeneity, which reflects ancient and recent admixture with neighboring populations, and important human migratory trends throughout the history.     

Polymorphism of DQA1 promoter in Italian population

We have investigated polymorphism in the 5′-URR of the DQA1 gene by PCR-SSO method in a group of 55 Italian healthy individuals olygotyped for DRB1, DQA1, DQB1 genes and in 20 10th IHWS cell lines as controls. We used primers and oligos (X and Y box) supplied by 12th IHWS and a DIG-11-ddUTP/AMPPD method. We have detected eight QAP variants (1.1,1.2,1.3,1.4,2.1,3.1,4.1,4.2) in our samples. As far as the association of DR/DQ haplotype and QAP sequences, we observed cases of one to one relationship (DQA1^*0201 and QAP2.1, DQA1^*0301 and QAP3.1, DQA1^*0401 and QAP4.2, DQA1^*0501 and QAP4.1); cases in which the same QAP allele was present in different DQA1-DRB1 haplotypes (QAP1.2 with DQA1^*0102 in DRB1^*15-DQB1^*0602 and DRB1^*16-DQB1^*0502 haplotypes or with DQA1^*0103 in the DRB1^*15-DQB1^*0601 haplotypes; QAP1.3 linked to DQA1^*0102, DQA1^*0103 or DQA1^*0104 in different haplotypes; QAP4.1 linked to DQA1^*0501 in DRB1^*11-DQB1^*0301, DRB1^*0301-DQB1^*0201, DRB1^*1303-DQB1^*0301 haplotypes or to DQA1^*0601 in DRB1^*0803-DQB1^*0301); cases where the same DQA1 allele is associated with different QAP sequences according to the DRB1 specificity (DQA1^*0102 allele with QAP1.2 or QAP1.4 in DRB1^*1302). Besides, we have observed that the QAP1.3, previously reported associated with DQA1^*0101-DRB1^*1401 haplotype, is really linked to DQA1^*0104-DRB1^*1401 haplotype. An intriguing data is that sometimes the same QAP is linked to different DQA1 alleles but to the same generic DRB1 allele: DRB1^*02 haplotype includes always the QAP1.2 variant but can bring different DQA1 alleles (^*0102 or ^*0103) and DRB1^*08 haplotype has always the QAP4.2 variant with different DQA1 alleles (^*0401 or ^*0601). The variability of linkage QAP-DQA1 can give further informations about HLA susceptibility in autoimmune diseases and in regulation of immune response in transplantation and oncology.     

Polymorphism of the DQA1 promoter region (QAP) and DRB1, QAP, DQA1, DQB1 haplotypes in the Dai minority population in South-Western China

We have investigated the polymorphism of the DQA1 promoter region (QAP) and we have deduced four point (DRB1, QAP, DQA1, DQB1) haplotypes of 60 unrelated healthy Dai minority individuals using the polymerase chain reaction and Dig-ddUTP labeled oligonucleotides. A total of eight QAP alleles (QAP1.1, 1.2, 1.3, 1.4, 3.1, 3.2, 4.1 and 4.2) were detected and two QAP alleles, QAP1.5 and QAP2.1 were absent in this population. The most predominant allele was QAP1.2 with 80% allele frequency. We also found that QAP alleles are in strong linkage disequilibrium with certain alleles of the neighboring loci DQA1 and DQB1. Complete positive association was found for QAP4.1-DQA1^*05, QAP4.2-DQA1^*0601, QAP1.2-DR2 group, QAP3.2-DRB1^*09, QAP4.1-DRB1^*03. A total of 28 different four point (DRB1-QAP-DQA1-DQB1) haplotypes were deduced and the most frequent haplotypes were DRB1^*1602-QAP1.2-DQA1^*0102-DQB1^*0502 (N = 18, H.f. = 15%) and DRB1^*09-QAP3.2-DQA1^*03-DQB1^*03032 (N = 18, H.f. = 15%) followed by the haplotypes DRB1^*1401-QAP1.3-DQA1^*01-DQB1^*0502, DRB1^*1202-QAP4.2-DQA1^*0601-DQB1^*0301 and DRB1^*1502-QAP1.2-DQA1^*0101-DQB1^*0501 with H.f. 9.1%, 6.7% and 5.0% respectively. The other 23 haplotypes were all less than 5% (H.f. 0.8%-5%). The relationship between the QAP alleles and DQA1 in the Dai minority is the same as that in the Chinese and the Caucasoid population.     

HLA-DR and -DQ alleles in Italian patients with melanoma

Abstract: Controversial data have been reported about HLA alleles and susceptibility to melanoma. Our investigation was undertaken to analyze the relationship between HLA alleles distribution in patients with melanoma and susceptibility to the tumor, in order to study the possible correlation between HLA class II DQA1, DQB1 and DRB1 genes involved in immune recognition, and melanoma, usually considered a highly immunogenic tumor. We therefore typed by means of PCR-SSP (sequence-specific primers) 53 Italian patients and 53 healthy random controls coming from the same geographic area. We observed a decrease of all haplotypes bearing DQB1*0301, DQB1*0302 and DQB1*0303 alleles but not of haplotype DRB1*11;DQA1*0501;DQB1*0301. Our results seem to support the hypothesis of a protective role of some DQ3-bearing haplotypic combinations in melanoma.     

The influence of age at onset and gender on the HLA-DQA1, DQB1 association in Chinese children with insulin dependent diabetes mellitus

Certain alleles of human leukocyte antigen (HLA)-DR and -DQ genes have been strongly associated with susceptibility and resistance to insulin- dependent diabetes mellitus (IDDM). To further clarify the association of HLA DQ alleles with IDDM and the influence of age at onset and gender on the association with IDDM, we investigated the association of HLA-DQA1, -DQB1 in 54 childhood onset Chinese (21 male) IDDM patients and 65 normal controls by using polymerase chain reaction-sequence specific primer (PCR-SSP). The mean age plus or minus SD at onset of IDDM patients was 8.37+/-3.54 year old. Our results revealed that the frequencies of DQA1 *0301, *0302, DQB1 *0201, and *0302 in IDDM patients were significantly higher than that in the control group (p < 0.025, < 0.005, < 0.001, and < 0.001, respectively). The frequency of DQA1 *0301, *0302, DQB1 *0201, and *0302 were susceptible alleles to IDDM with relative risks of 2.0, 3.5, 5.0 and 4.3, respectively. The protective alleles to IDDM were DQA1 *0101, *0103, DQB1 *0301, *0503, and *0602. We divided IDDM patients into three groups according to age at onset (1-5, 6-10, and 11-15 years old). The frequency of DQA1 *0302 decreased as age increased, and the frequency of DQA1 *0501 increased as age increased. Our results also showed that male IDDM patients had higher frequencies of DQA *0501, DQB1 *0201 than female IDDM patients (p < 0.025 and < 0.025, respectively), while female IDDM patients had higher frequencies of DQB1 *0502 than male IDDM patients (p < 0.05). In our study significant susceptibility haplotypes to IDDM were DQA1 *0301-DQB1 *0302, DQA1 *0501-DQB1 *0201, DQA1 *0301-DQB1 *0201, and DQA *0302-DQB1 *0201.     

Distribution of HLA-DQA1 and -DQB1 alleles and DQA1-DQB1 genotypes among Senegalese patients with insulin-dependent diabetes mellitus

Transracial analysis is one method for distinguishing primary associations between insulin-dependent diabetes mellitus (IDDM) and HLA II alleles from those related to linkage disequilibrium. Black people have different DR-DQ relationships from other races and are a useful group to investigate HLA-D regions associated with IDDM. In this study, we compared the frequencies of HLA-DQA1 and DQB1 alleles in Senegalese IDDM and control subjects. DQA1*0301 was positively associated with insulin-dependent diabetes mellitus (p<10^-9, OR 5.21), as were DQB1*0201 and *0302 (p<10^-7 OR=3.55, p<10^-3 OR=3.20, respectively). The positive associations with DQA1*0301, DQB1*0201 and DQB1*0302 are consistent with all racial groups investigated. However, taken together, the data in Senegalese population show that susceptibility and resistance to IDDM are associated both with particular haplotypes and DQA1-DQB1 heterodimers.     

DQA103 subtypes have different associations with DRB1 and DQB1 alleles

Polymorphisms outside the hypervariable regions of HLA class II alleles that do not affect the peptide-binding site are probably not under selective pressure and could therefore be useful as markers of the evolutionary pathways of the HLA class II haplotypes. We have analyzed such a polymorphism in the variants of DQA1^*03, which differ at residue 160 encoded in exon 3. Our study included homozygous BCLs of the 10th IHWS and samples of a multiracial panel of 723 unrelated subjects which were also typed for allelic variations in exon 2 by hybridization with SSOP. BCLs having DQA1^*03 and 131 selected DQA1^*03-positive samples were typed for the dimorphism in exon 3 that distinguishes DQA1^*0301 and DQA1^*0302. DQA1^*0301 was found to be exclusively associated with DQB1^*0302, while samples carrying DQB1^*0201, 0301, 0303, and 0401 always had DQA1^*0302. A few haplotypes carrying DQB1^*0302 had DQA1^*0302. The fact that DQA1^*0301 is completely included in DQB1^*0302, and not vice versa, suggests that DQA1^*0301 may have arisen from a mutation in a haplotype containing DQA1^*0302-DQB1^*0302. DQB1^*0302 was found to be associated with all DR4 subtypes, suggesting possibly that the current variants of DRB1-DR4 may be of more recent origin. DRB1^*0405 was the only subtype of DR4 which was not associated with DQA1^*0301 and had multiple associations with the DQB1 alleles, therefore, perhaps representing the oldest allele of this group.     

Molecular analysis of HLA-DRB1, -DQA1 and -DQB1 polymorphism in Turkey

We report the evaluation of MHC class II polymorphism in the population of Turkey. HLA-DRB1, -DQA1 and -DQB1 have been investigated by polymerase chain reaction and sequence-specific oligonucleotide probe hybridisations (PCR/SSO) and sequence-specific priming (SSP) in 250 randomly selected healthy individuals. We also report the allelic distribution of these genes. The most frequent alleles detected were DRB1*1101 (0.104), *0301 (0.092), *0701 (0.090), DQA1*0501 (0.334), *0102 (0.164) and *03 (0.148) and DQB1*0301 (0.256), *02 (0.164), *0302 (0.128). The frequent 'putative' three-locus haplotypes carry the most frequent alleles at these loci. The most frequently detected class II "haplotypes" are DRB1*1101 DQA1*0501 DQB1*0301 (0.100), DRB1*0301 DQA1*0501 DQB1*02 (0.092) and DRB1*0701 DQA1*0201 DQB1*02 (0.072). The distribution of alleles and 'putative' haplotypes has shown common features with other Mediterranean populations. The results extend the HLA map to another Mediterranean country and provide a database for further HLA-disease association studies and transplantation applications.     

IDDM与HLA-DQA1及其启动子QAP 的相关性研究

目的 研究胰岛素依赖性糖尿病（IDDM）的易感性与HLA－DQA1及其启动子QAP基因多态性是否存在关联。方法 采用PCR－RFLP分析DQA1等位基因多态性;采用PCR－SSO检测QAP多态性。结果 等位基因分析发现,患者中DQA1＊0301、QAP3．2等位基因频率显著高于正常人（RR＝2．80、2．43,P＜0．01）;而DQA1＊0601、QAP4．2在患者中分布频率较正常人显著降低（RR＝0．10,P＜0．025）。启动子与结构基因连锁分析表明：QAP3．2－DQA1＊0301单元型与IDDM关联,QAP3．1－DQA1＊0301与IDDM无关联;QAP4．20－DQA1＊0601则具有保护作用。结论 1．IDDM与HLA的关联不仅存在于结构基因,而且也存在于启动子;2．同一结构基因与不同的启动子连锁可呈现不同的关联格局。