HLA class II profile and distribution of HLA-DRB1 and HLA-DQB1 alleles and haplotypes among Lebanese and Bahraini Arabs

The gene frequencies of HLA class II alleles were studied in 95 healthy Lebanese Arab and 72 healthy Bahraini Arab subjects. Our aim was to establish the genetic relationship between Bahraini and Lebanese Arabs in terms of HLA class II gene and haplotype frequencies and to compare these results with frequencies for other countries with populations of Caucasian and non-Caucasian descent. Subjects were unrelated and of both sexes, and HLA-DRB1 and -DQB1 genotyping was done by the PCR sequence-specific primer technique. Comparative analysis of the HLA-DR and -DQ alleles revealed differences in the allelic distribution among Bahraini and Lebanese subjects. Analysis of the 25 HLA-DRB1 alleles that have been investigated showed that the DRB1*040101 and DRB1*110101 alleles were more frequent among Lebanese, whereas DRB1*030101 and DRB1*160101 alleles were more frequent among Bahrainis. Similarly, of the seven HLA-DQB1 alleles analyzed, the presence of DQB1*0201 was more frequent among Bahrainis, whereas DQB1*030101 was more frequent among Lebanese. The DRB1*160101-DQB1*050101 (0.1318 versus 0.0379%) and DRB1*030101-DQB1*0201 (0.1202 versus 0.0321%) haplotypes were more frequent among Bahrainis, while the DRB1*110101-DQB1*030101 (0.3142 versus 0.1198%) and DRB1*040101-DQB1*0302 (0.1416 versus 0.0278%) haplotypes were more frequent in Lebanese subjects. Furthermore, a high prevalence of the DRB1*040101-DRB1*110101-DQB1*0302-DQB1*030101 (12.63 versus 1.35%, P = 0.015) and the homozygous DRB1*110101-DRB1*110101-DQB1*030101-DQB1*030101 (7.37 versus 0.00%, P = 0.046) genotypes was seen among Lebanese, and DRB1*070101-DRB1*160101-DQB1*0201-DQB1*050101 (6.76 versus 0.00%, P = 0.034) was seen more frequently among Bahraini subjects. Our results underline significant differences between these two populations in HLA class II distribution, provide basic information for further studies of major histocompatibility complex heterogeneity among Arabic-speaking countries, and serve as a reference for further anthropological studies.     

Specific HLA-DRB and -DQB alleles and haplotypes confer disease susceptibility or resistance in Bahraini type 1 diabetes patients

Insofar as genetic susceptibility to type 1 diabetes is associated with HLA class II genes, with certain allelic combinations conferring disease susceptibility or resistance, this study assessed the distributions of HLA-DR and -DQ among 107 unrelated patients with type 1 diabetes and 88 healthy controls from Bahrain, all of Arab origin. The HLA-DRB and -DQB genotypes were determined by PCR-sequence-specific priming. The following alleles showed the strongest association with type 1 diabetes among patients versus controls according to their frequencies: DRB1*030101 (0.430 versus 0.097; P < 0.001), DRB1*040101 (0.243 versus 0.034; P < 0.001), DQB1*0201 (0.467 versus 0.193; P < 0.001), and DQB1*0302 (0.229 versus 0.091; P < 0.001). When the frequencies of alleles in controls were compared to those in patients, negative associations were seen for DRB1*100101 (0.085 versus 0.014; P < 0.001), DRB1*110101 (0.210 versus 0.060; P < 0.001), DQB1*030101 (0.170 versus 0.075; P = 0.006), and DQB1*050101 (0.335 versus 0.121; P < 0.001). In addition, the DRB1*030101-DQB1*0201 (70.1 versus 22.7%; P < 0.001) and DRB1*030101-DQB1*0302 (21.5 versus 0.0%; P < 0.001) genotypes were more prevalent among patients, thereby conferring disease susceptibility, whereas the DRB1*100101-DQB1*050101 (20.5 versus 2.8%; P < 0.001), DRB1*110101-DQB1*030101 (28.4 versus 8.4%; P < 0.001), and DRB1*110101-DQB1*050101 (30.7 versus 0.9%; P < 0.001) genotypes were more prevalent among controls, thus assigning a protective role. These results confirm the association of specific HLA-DR and -DQ alleles and haplotypes with type 1 diabetes and may underline several characteristics that distinguish Bahraini patients from other Caucasians patients.     

Susceptible and protective human leukocyte antigen class II alleles and haplotypes in bahraini type 2 (non-insulin-dependent) diabetes mellitus patients

Whereas the genetic risk for type 1 diabetes is linked to human leukocyte antigen (HLA) class II genes, the HLA association in type 2 (non-insulin-dependent) diabetes is less clear. The association between HLA class II genotypes and type 2 diabetes was examined in adult Bahrainis, an Arab population with a high prevalence of type 2 diabetes. HLA-DRB1* and -DQB1* genotyping of 86 unrelated type 2 diabetes patients (age, 51.6+/-8.2 years; mean duration of diabetes, 7.7+/-7.1 years) who had a strong family history of diabetes (52 of 72 versus 0 of 89 for controls, P<0.001) and 89 healthy subjects was done by PCR-sequence-specific priming. DRB1*040101 (0.1221 versus 0.0562, P=0.019) and DRB1*070101 (0.2151 versus 0.0843, P<0.001) were positively associated, while DRB1*110101 (0.0698 versus 0.1461, P=0.014) and DRB1*160101 (0.0640 versus 0.1236, P=0.038) were negatively associated with type 2 diabetes. DRB1*040101-DQB1*0302 (0.069 versus 0.0007; P=0.004), DRB1*070101-DQB1*0201 (0.178 versus 0.0761, P=0.007), DRB1*070101-DQB1*050101 (0.125 versus 0.0310, P=0.002), and DRB1*150101-DQB1*060101 (0.0756 versus 0.0281, P=0.008) were more prevalent among patients, while DRB1*160101-DQB1*050101 (0.0702 versus 0.0349, P=0.05) was more prevalent among controls, conferring disease susceptibility or protection, respectively. In Bahrainis with type 2 diabetes, there is a significant association with select HLA class II genotypes, which were distinct from those in type 1 diabetes.     

HLA-DPB1, -DRB1, and -DQB1 polymorphism defined in Ewenki ethnic minority of China Inner Mongolia Autonomous Region

In the present study, DNA typing for human leucocyte antigen (HLA)-DPB1, -DRB1, and -DQB1 was performed using polymerase chain reaction-sequence-based-typing (PCR-SBT) method on 94 randomly selected, healthy, unrelated individuals from the Ewenki ethnic population in Inner Mongolia Autonomous Region of China. A total of 64 alleles: 25 in DRB1, 19 in DQB1 and 20 in DPB1, were found. Among the 25 detected DRB1 alleles, DRB1*090102, DRB1*030101, DRB1*040101, DRB1*070101, and DRB1*120101/1206 were commonly observed, with frequencies of 16.0%, 13.3%, 10.1%, 7.4%, and 7.4%, respectively. The most predominant DQB1 allele was DQB1*030101/0309 with the frequency of 27.7%, followed by DQB1*0201/0202 (19.7%), DQB1*030302 (12.8%), DQB1*060101/060103 (6.4%), and DQB1*050201 (5.9%). Of the 20 detected DPB1 alleles, DPB1*020102 was the most frequent allele with the frequency of 25.5%. DPB1*0402 (21.3%), DPB1*0401 (20.2%), DPB1*0501 (10.6%) and DPB1*4101 (3.7%) were also very frequent alleles. The most frequent two-locus haplotypes observed in the Ewenki were: DRB1*030101-DQB1*0201/0202(10.7%), DRB1*090102-DQB1*03032(9.8%), DRB1*070101-DQB1*0201/0202 (5.5%), DRB1*070101-DQB1*030302 (5.2%) and DRB1*120101/1206-DQB1*030101/0309 (4.6%). The distribution of the HLA class II alleles and haplotypes frequencies as well as the dendrogram showed that the Ewenki population belongs to the northern group of Chinese.     

Association of selective HLA class II susceptibility-conferring and protective haplotypes with type 2 diabetes in patients from Bahrain and Lebanon

The association of HLA class II with type 2 diabetes (T2DM) was investigated in Bahraini and Lebanese subjects. DRB1*070101 (Lebanese and Bahraini) and DQB1*0201 (Lebanese) were susceptibility-conferring alleles, and unique susceptibility-conferring/protective haplotypes were found in both patient groups. Regression analysis confirmed that DRB1*070101-DQB1*0201 (Bahraini) and DRB1*110101-DQB1*0201 (Lebanese) were susceptibility-conferring haplotypes.     

Polymorphism of human leukocyte antigen-DRB1, -DQB1, and -DPB1 genes of Shandong Han population in China

In the present study, polymerase chain reaction-sequence-based typing (PCR-SBT) was used to analyze human leukocyte antigen (HLA)-DRB1, -DQB1, and -DPB1 alleles of 98 unrelated healthy Shandong Han individuals. A total of 60 alleles, in which 28 in DRB1, 15 in DQB1 and 17 in DPB1 were found. Among the 28 detected DRB1 alleles, DRB1*150101, DRB1*070101, DRB1*090102, DRB1*120201, and DRB1*080302 were commonly observed, with frequencies of 16.3%, 11.2%, 10.2%, 8.2%, and 5.6%, respectively. The most predominant DQB1 allele was DQB1*030101/0309 with the frequency of 20.4%, followed by DQB1*0201/0202 (14.8%), DQB1*0602 (14.3%), DQB1*030302 (12.2%), and DQB1*060101/060103 (10.7%). Of the 17 detected DPB1 alleles, DPB1*0501 was the most frequent allele with the frequency of 37.2%. DPB1*020102 (18.4%), DPB1*040101 (11.2%), DPB1*0402 (7.1%), and DPB1*1701 (6.6%) were also very frequent alleles. A total of 53 estimated DRB1-DQB1 two-locus haplotypes were observed in Shandong Han population, of which DRB1*150101-DQB1*0602 was the most predominant, followed by DRB1*090102-DQB1*030302, DRB1*070101-DQB1*0201/0202 DRB1*120201-DQB1*030101/0309, and DRB1*080302- DQB1*060101/060103. The distribution of the HLA class II alleles and haplotypes frequencies as well as the dendrogram showed that the Shandong Han population belongs to the northern group of Chinese. The data have implications for anthropological studies and disease associations.     

Class II HLA allele polymorphism: DRB1, DQB1 and DPB1 alleles and haplotypes in the New Zealand Maori population

Class II alleles of interest to transplantation comprise the DRB1, DQB1 and DPB1 loci. Sequence-based typing was used to determine the class II allelic variability present in New Zealand Maori, a population with close genetic ties to Polynesia and known anthropological and linguistic connections to mainland Asia. The most common DRB1 alleles identified were DRB1*1201, DRB1*110101, DRB1*0403 and DRB1*080302, with frequencies of 21.5%, 14%, 11.25% and 9.25%, respectively. Standard linkages between the DRB1 locus and the DRB3, 4 and 5 loci were maintained, with no novel patterns identified. The most common DQB1 alleles identified were DQB1*030101, DQB1*060101, DQB1*020101, DQB1*0602 and DQB1*050201, with frequencies of 29.5%, 8%, 7.8%, 6.4% and 6.2%, respectively. The most common DPB1 alleles identified were DPB1*0501, DPB1*040101 and DPB1*020102, with frequencies of 40.2%, 28.89% and 15.83%, respectively. A total of 80 estimated DRB1-DQB1 two-locus haplotypes were detected. DRB1*1201-DQB1*030101 was the most frequent (15.40%) haplotype, followed by DRB1*110101-DQB1*030101 (9.97%), DRB1*0403-DQB1*030201 (7.37%) and DRB1*080302-DQB1*060101 (5.96%). The allelic variation determined is being used in further analysis of the requirement for bone marrow transplantation in the New Zealand Maori population and has implications for optimal ethnic donor distribution on the New Zealand Bone Marrow Donor Registry, anthropological studies and disease association.     

Human leucocyte antigen class II DRB1 and DQB1 associations in human immunodeficiency virus-infected patients of Mumbai,India

The pathogenesis of human immunodeficiency virus (HIV) infection clearly involves immunoregulatory host factors and products of major histocompatibility complex class II genes, which present antigenic peptides to the T-cell receptor on CD4+ cells, which in turn increase the production of specific antibodies and cytotoxic T lymphocytes. The main objective of this study was to determine the associations of human leucocyte antigen (HLA) DRB1 and DQB1 alleles and their haplotypes in 210 HIV-1-infected patients and compare them with 129 healthy normal individuals with same ethnic background. The HLA DRB1 and DQB1 alleles were genotyped using polymerase chain reaction product and sequence-specific probes for reverse line hybridization, analysed with the Invitrogen Dynal PMP software. Our results revealed a highly significant increase of HLA DRB1*0902 [odds ratio (OR) = 17.12; P = 0.004], DQB1*030103 (OR = 53.53; P = 4.61E-07) and DQB1*050201 (OR = 16.26; P = 0.0002) alleles while in contrast highly significant decrease in frequency of HLA DQB1*030101 (OR = 0.36; P = 0.0002), DQB1*050301 (OR = 0.22; P < 0.0001) and DQB1*060101 (OR = 0.43; P < 0.0001) among the HIV-1-infected patients when compared with the controls. The haplotype DRB1*0902-DQB1*030103 (OR = 10.65; P = 0.06) was significantly increased in HIV1 patients, while haplotypes DRB1*150101–DQB1*060101 (OR = 0.386, P < 0.0001), DRB1*030101–DQB1*020101 (OR = 0.197, P = 0.004) and DRB1*070101–DQB1*0202 (OR = 0.167, P = 0.001) were significantly decreased. Our results indicate clearly that there are HLA class II alleles involved in the susceptibility to and protection from HIV-1 infection in our study group and further they vary in different ethnic groups reported in literature.     

Autoantibody epitopes to the smaller isoform of glutamate decarboxylase do not differ in Swedish and Japanese type 1 diabetes patients and may be associated with high-risk human leucocyte antigen class II alleles

Type 1 diabetes (T1D) is an autoimmune disease with a strong human leucocyte antigen (HLA) class II association. Depending on geographic locations, the disease-associated HLA class II alleles vary. We evaluated the beta cell-specific autoimmunity reflected in autoantibodies directed to the smaller isoform of glutamate decarboxylase (GAD65) in Japanese and Swedish T1D patients. GAD65Ab epitope specificities were assessed using GAD65-specific recombinant Fab. GAD65Ab epitope specificities did not differ between Swedish and Japanese patients. Only recognition of the MICA-4-defined middle epitope was significantly stronger in the Japanese T1D patient group compared to the Swedish T1D patients (P = 0.001). Binding to the b96.11-defined middle epitope was substantial in both groups and showed significant associations with high-risk HLA class II haplotypes. In the Japanese T1D group the association was with haplotype DRB1*0802-DQB1*0302 (P = 0.0008), while in the Swedish T1D patients binding to the b96.11-defined epitope as associated with the presence of high-risk HLA genotypes DR3-DQB1*0201 and/or DR4-DQB1*0302 (P = 0.02). A significant association between reduction in binding in the presence of recombinant Fab (rFab) DPD and high-risk allele DQB1*0201 was found (P = 0.008) in the Swedish T1D patients only. We hypothesize that epitope-specific autoantibodies effect the peptide presentation on HLA class II molecules by modulating antigen uptake and processing. Molecular modelling of the high-risk HLA class II molecules will be necessary to test whether these different molecules present similar peptide-binding specificities.     

Evidence for HLA class II susceptible and protective haplotypes for osteomyelitis in pediatric patients with sickle cell anemia

We investigated the association of human leukocyte antigen (HLA) class II alleles and haplotypes with the pathogenesis of sickle cell anemia (SCA) osteomyelitis. SCA patients comprised 42 patients with osteomyelitis and 150 patients without osteomyelitis; HLA-DRB1* and HLA-DQB1* genotyping was performed by polymerase chain reaction-sequence-specific priming (SSP). DRB1*100101 (P value corrected for the number of different alleles tested, Pc=0.003) was positively associated with osteomyelitis. At the haplotype level, DRB1*100101-DQB1*050101 (Pc=0.001) was more prevalent among patients, while DRB1*030101-DQB1*0201 (Pc=0.020) and DRB1*040101-DQB1*0302 (Pc=0.039) were more prevalent among SCA controls, thereby conferring disease susceptibility or protection to these haplotypes, respectively. These results show that specific HLA haplotypes influence SCA osteomyelitis risk and that specific HLA types may serve as markers for identifying SCA patients at high risk for osteomyelitis.     

Autoimmune Type 1 Diabetes Genetic Susceptibility Encoded by Human Leukocyte Antigen DRB1 and DQB1 Genes in Tunisia

Human leukocyte antigen (HLA) class II genes contribute to the genetic susceptibility to type 1 diabetes (T1D), and susceptible alleles and haplotypes were implicated in the pathogenesis of T1D. This study investigated the heterogeneity in HLA class II haplotype distribution among Tunisian patients with T1D. This was a retrospective case control study done in Monastir in central Tunisia. The subjects comprised 88 T1D patients and 112 healthy controls. HLA-DRB1 and -DQB1 genotyping was done by PCR-sequence-specific priming. Significant DRB1 and DQB1 allelic differences were seen between T1D patients and controls; these differences comprised DRB1*030101 and DQB1*0302, which were higher in T1D patients than in control subjects, and DRB1*070101, DRB1*110101, DQB1*030101, and DQB1*060101, which were lower in T1D patients than in control subjects. In addition, the frequencies of DRB1*030101-DQB1*0201 and DRB1*040101-DQB1*0302 were higher in T1D patients than in control subjects, and the frequencies of DRB1*070101-DQB1*0201 and DRB1*110101-DQB1*030101 haplotypes were lower in T1D patients than in control subjects. Multiple logistic regression analysis revealed the positive association of DRB1*030101-DQB1*0201 and DRB1*040101-DQB1*0302 and the negative association of only DRB1*070101-DQB1*0201 haplotypes with T1D. Furthermore, a significantly increased prevalence of DRB1*030101-DQB1*0201 homozygotes was seen for T1D subjects than for control subjects. Our results confirm the association of specific HLA-DR and -DQ alleles and haplotypes with T1D in Tunisians. The identification of similar and unique haplotypes in Tunisians compared to other Caucasians highlights the need for evaluating the contribution of HLA class II to the genetic susceptibility to T1D with regard to haplotype usage and also to ethnic origin and racial background.Type 1 (insulin-dependent) diabetes (T1D) is the most prevalent form of diabetes in children and young adults (12, 17) and results from autoimmune CD4⁺ and CD8⁺ T-cell-directed destruction of insulin-producing pancreatic ß islet cells, leading to irreversible hyperglycemia and related complications (4, 22). In addition to environmental factors, there is a strong genetic component to T1D pathogenesis, of which the human leukocyte antigen (HLA) locus, in particular the class II region (DR and DQ), account for 40 to 50% of T1D familial clustering (13, 30). This was evidenced by the enrichment of DR3, DR4, DQ2, and DQ8, and the lower prevalence of DR15 or DQ6.2 alleles among T1D patients, thereby assigning a susceptible or protective role for these alleles in T1D pathogenesis, respectively (3, 16, 21).The fact that not all carriers of a specific high-risk DR or DQ variant develop the disease and the strong linkage disequilibrium between select DRB1 and DQB1 alleles (28) indicate that the pathogenesis of T1D results from the complex interaction between several genes within the class II region, in which specific DRB1-DQB1 haplotypes contribute to disease susceptibility. Accordingly, the enrichment or decreased prevalence of select DRB1-DQB1 haplotypes in T1D patients imparts disease susceptibility or protection, respectively (3, 18, 24). This susceptibility or protection effect disappears when a different DRB1 or DQB1 allele replaces the specific allele in the haplotype (29). The contribution of specific HLA haplotypes toward T1D susceptibility depends on the ethnic/racial background (26), which was highlighted by the positive association of DRB1*030101-DQB1*0201 and DRB1*040101-DQB1*0302 haplotypes with T1D among Caucasians (3, 16) compared to DRB1*0405-DQB1*0401 and DRB1*0901-DQB1*0303 haplotypes and T1D in Japanese (18), while DRB1*1501-DQB1*0602 appeared to be protective of T1D in all populations (3, 16, 18). This indicates that association of a specific class II allele and DRB1-DQB1 haplotype with T1D must be evaluated in the context of the specific ethnic/racial background (26).We previously reported an association between HLA DRB1 and DQB1 alleles and haplotypes in Tunisian T1D patients (n = 50) and control subjects (n = 50) and identified two susceptible haplotypes (DRB1*030101-DQB1*0201 and DRB1*040101-DQB1*0302), but no protective haplotypes (27). Using haplotype estimation and regression analysis, here, we extend our investigation of HLA class II and T1D risk on a large sample size by confirming the association of these haplotypes and identified an additional T1D-protective haplotype.     

HLA class II haplotypes distinctly associated with vaso-occlusion in children with sickle cell disease

We investigated the association of HLA class II alleles and haplotypes with sickle cell anemia vaso-occlusive crisis (VOC). DRB1*100101 was positively associated, while DRB1*140101, DRB1*150101, and DQB1*060101 were negatively associated, with VOC. Both susceptible (DRB1*100101-DQB1*050101) and protective (DRB1*110101-DQB1*030101 and DRB1*150101-DQB1*060101) haplotypes were identified, indicating that HLA class II haplotypes influence VOC risk.     

Molecular analyses of HLA-DRB1, -DPB1, and -DQB1 in Jing ethnic minority of Southwest China

In the present study, DNA typing for HLA-DRB1, DQB1 and DPB1 was performed using polymerase chain reaction-sequencing based typing (PCR-SBT) method in 144 random selected Jing ethnic individuals inhabiting in South China. Allele frequencies and two-locus haplotypes (DRB1-DQB1) were statistically analyzed and 20 DPB1 alleles, 27 DRB1 and 20 DQB1 were detected. The most frequent DPB1 allele was DPB1*0501 with the percentage of 36.9% followed by DPB1*1301 (15.7%), DPB1*0401 (11.0%) and DPB1*020102 (9.8%). Among the 27 detected DRB1 alleles, DRB1*120201 (13.8%) was most commonly observed followed by DRB1*150201, *030101 and *090102 alleles with the frequencies of 9.4%, 9.1% and 8.3%, respectively. Among the 20 detected DQB1 alleles the most predominant one was DQB1*030101/0309 (19.9%). DQB1*050201 (19.1%), DQB1*0201/0202 (16.1%) and DQB1*050101 (12.3%) were also frequently observed in Jing population. Statistical analysis of two-locus haplotypes showed that DRB1*120201-DQB1*030101/DRB1*120201-DQB1*0309 (HF = 9.4%, D = 6.65x10(-2)) was most predominant followed by DRB1*030101-DQB1*0201/DRB1*030101-DQB1*0202 (HF = 8.1%, D = 6.66 x 10(-2)). The comparison of HLA class II allele and haplotype frequencies in Jing with those in other populations all over the world and a dendrogram based on the DRB1, DQB1 and DPB1 genes suggested that Jing ethnic population has an origin of Southeast Asia and is belonged to the southern group of Chinese populations.     

HLA in Czech adult patients with autoimmune diabetes mellitus: comparison with Czech children with type 1 diabetes and patients with type 2 diabetes.

Type 1 diabetes results from an autoimmune insulitis, associated with HLA class II alleles. The evidence about HLA allele association is not clear in patients diagnosed after 35 years of age. In this study we have analyzed HLA alleles of DQB1 and DRB1 genes by sequence specific primer (SSP)-PCR technique in adult patients with disease onset after 35 years of age. Two hundred and eighty-one patients were divided into three groups according to the insulin therapy, the level of C peptide (CP), and GAD antibodies (anti-GAD). Group 1 (type 1 diabetes in adults) was characterized by CP less than 200 pmol/L and anti-GAD more or less than 50 ng/mL (n = 80). All of them had insulin therapy within 6 months after diagnosis. Group 2 latent autoimmune diabetes mellitus in adults (LADA) was defined by a minimum 6-month-long phase after diagnosis without insulin therapy, and was characterized by CP more than 200 pmol/L and anti-GAD more than 50 ng/mL (n = 70). Group 3 (type 2 diabetes) was characterized by CP more than 200 pmol/L and anti-GAD less than 50 ng/mL (n = 131). None ever had insulin therapy. In group 1, there was increased frequency of DRB1*04 (45.0% vs. controls 14.1%, OR = 5.0, P < 0.0005) and DQB1*0302 alleles (43.3% vs. controls 11.1%, OR = 6.1, P < 0.00005). There was increased frequency of DRB1*03 and DQB1*0201, and decreased frequency of DQB1*0602 (3.3% vs. controls 20.2%), but it was not significant. In group 2, there was a significantly increased frequency of DRB1*03 only (50.0% vs. controls 21.2%, OR = 3.7, P < 0.05). Compared with children with type 1 diabetes and adults with type 2 diabetes (group 3), we conclude that the presence of predisposing DQB1 alleles in adults with type 1 diabetes decreases with the age, probably due to environmental factors. Only the DRB1*03, but not the DQB1 gene, becomes the main predisposing allele in LADA patients. These findings suggest that the presence of HLA-DQB1*0302 identifies patients at high risk of requiring insulin treatment. Type 1 diabetes mellitus (DM) in children or adults may have partly different immunogenetic etiopathogenesis than LADA.     

Estimation of diabetes risk in Brazilian population by typing for polymorphisms in HLA-DR-DQ, INS and CTLA-4 genes

The study aimed to further characterise HLA encoded risk factors of type 1 diabetes (T1D) in Brazilian population and test the capability of a low resolution full-house DR-DQ typing method to find subjects at diabetes risk. Insulin and CTLA-4 gene polymorphisms were also analysed. The method is based on an initial DQB1 typing supplemented by DQA1 and DR4 subtyping when informative. Increased frequencies of both (DR3)-DQA1*05-DQB1*02 and DRB1*04-DQA1*03-DQB1*0302 haplotypes were detected among patients. DRB1*0401, *0402, *0404 and *0405 alleles were all common in DQB1*0302 haplotypes and associated with T1D. (DRB1*11/12/1303)-DQA1*05-DQB1*0301, (DRB1*01/10)-DQB1*0501, (DRB1*15)-DQB1*0602 and (DRB1*1301)-*0603 haplotypes were significantly decreased among patients. Genotypes with two risk haplotypes or a combination of a susceptibility associated and a neutral haplotype were found in 78 of 126 (61.9%) T1D patients compared to 8 of 75 (10.7%) control subjects (P < 0.0001). Insulin gene -2221 C/T polymorphism was also associated with diabetes risk: CC genotype was found among 83.1% of patients compared to 69.3% of healthy controls (P=0.0369, OR 1.98) but CTLA-4 gene +49 A/G polymorphism did not significantly differ between patients and controls. Despite the diversity of the Brazilian population the screening sensitivity and specificity of the used method for T1D risk was similar to that obtained in Europe.     

Relative predispositional effects of HLA class II DRB1-DQB1 haplotypes and genotypes on type 1 diabetes: a meta-analysis

The direct involvement of the human leukocyte antigen class II DR-DQ genes in type 1 diabetes (T1D) is well established, and these genes display a complex hierarchy of risk effects at the genotype and haplotype levels. We investigated, using data from 38 studies, whether the DR-DQ haplotypes and genotypes show the same relative predispositional effects across populations and ethnic groups. Significant differences in risk within a population were considered, as well as comparisons across populations using the patient/control (P/C) ratio. Within a population, the ratio of the P/C ratios for two different genotypes or haplotypes is a function only of the absolute penetrance values, allowing ranking of risk effects. Categories of consistent predisposing, intermediate ('neutral'), and protective haplotypes were identified and found to correlate with disease prevalence and the marked ethnic differences in DRB1-DQB1 frequencies. Specific effects were identified, for example for predisposing haplotypes, there was a statistically significant and consistent hierarchy for DR4 DQB1*0302s: DRB1*0405 =*0401 =*0402 > *0404 > *0403, with DRB1*0301 DQB1*0200 (DR3) being significantly less predisposing than DRB1*0402 and more than DRB1*0404. The predisposing DRB1*0401 DQB1*0302 haplotype was relatively increased compared with the protective haplotype DRB1*0401 DQB1*0301 in heterozygotes with DR3 compared with heterozygotes with DRB1*0101 DQB1*0501 (DR1). Our results show that meta-analyses and use of the P/C ratio and rankings thereof can be valuable in determining T1D risk factors at the haplotype and amino acid residue levels.     

The HLA-DRB, -DQB polymorphism and anti-insulin antibody response in Slovenian patients with type 1 diabetes.

A combination of specific HLA class II antigens and the presence of type 1 diabetes (T1D)-related antibodies has a high positive predictive value for T1D but low sensitivity. The aim of the present study was to determine the frequencies of HLA-DRB-DQB deduced haplotypes associated with susceptibility and protection in Slovenian patients with established T1D, to evaluate the relationship between the HLA-DRB1-QBP-DQB1 haplotypes and the presence of insulin autoantibodies (IAA) and glutamic acid decarboxylase antibodies (GADA), and to access the possible impact of polymorphic QBP promoters on this relationship. A cohort of 135 patients with T1D (age 17.5 +/- 7.0 years, duration of T1D 9.14 +/- 6.3 years) was investigated. HLA-DRB1 and DQB1 alleles were typed using the polymerase chain reaction (PCR)-reverse line blot method. QBP promoter region alleles were determined using PCR-sequence-specific oligonucleotide hybridization (SSO) and PCR-sequence-specific primers (SSP). IAA and GADA antibodies were determined by enzyme-linked immunosorbent assay (ELISA). The chi-square test with Yates' correction was used for statistical analysis. Deduced haplotypes DRB1*0301-DQB1*0201 (P = 0.0001, OR = 3.4), DRB1*0401-DQB1*0302 (P = 0.0001, OR = 29.8), and DRB1*0402-DQB1*0302 (P = 0.008, OR = 4.7) were significantly more common, and DRB1*1501-DQB1*0602 (P = 0.0001, OR = 0.03) significantly less common in the investigated cohort than in a Slovenian control group. The highest risk and the strongest protective HLA-DR-DQ haplotypes found in Slovenian patients with T1D did not differ from those found in other Caucasian populations. While the DRB1*0301-QBP2.1-DQB1*0201 haplotype, where QBP2.1 did not help to further distinguish DQB1*0201-possessing haplotypes in IAA-positive and IAA-negative patients, was strongly associated with the presence of IAA, the DRB1*0101-QBP5.12-DQB1*0501 haplotype, although not protective compared to the control population, was associated with an absence of IAA in the investigated cohort. It is suggested that there may be a combined influence of the QBP5.12 promoter and the DQB1*0501 functional molecule on reduced IAA production.     

Type 1 diabetes in Jewish Ethiopian immigrants in Israel: HLA class II immunogenetics and contribution of new environment

The interrelationship between human leukocyte antigen immunogenetics and environmental factors and their contribution to the emergence of type 1 diabetes (T1D) were studied in Jewish immigrants from Ethiopia in Israel. This community displays high incidence of T1D, and is unique both by its ethnic segregation and its rapid exposure to a new environment after the immigration. The study population consisted of 152 Ethiopian Jews living in Israel, 33 with T1D and 119 unrelated controls. Human leukocyte antigen class II susceptible and protective alleles in the Jewish Ethiopian patients were similar to those in patients of other ethnic groups in Israel and in non-Jewish Ethiopian patients, with a few exceptions. Three haplotypes were markedly associated with diabetes in Jewish Ethiopian patients: DRB1*0301 DQA1*05 DQB1*02 (OR 4.4, p < 0.001); DRB1*0404 DQA1 03 DQB1*0302 (OR 19.2, p = 0.006), and DRB1*0405 DQA1*03 DQB1*0302 (OR 87.8, p < 0.001). The highly susceptible allele DRB1*0301 was more common in the general Ethiopian population (25.2%) than in all other ethnic groups in Israel, which may render this community prone to the disease. The age at onset of disease in patients with two susceptible haplotypes was negatively correlated with the duration of living in Israel (r = −0.621, p = 0.04). We concluded that ongoing exposure of genetically predisposed immigrants from Ethiopia to diabetogenic environmental factors eventually leads to a high incidence of overt diabetes in this ethnic group.     

Complex interaction between HLA DR and DQ in conferring risk for childhood type 1 diabetes.

Type 1 (insulin-dependent) diabetes mellitus is associated with HLA DR and DQ factors, but the primary risk alleles are difficult to identify because recombination events are rare in the DQ-DR region. The risk of HLA genotypes for type 1 diabetes was therefore studied in more than 420 incident new onset, population-based type 1 diabetes children and 340 age, sex and geographically matched controls from Sweden. A stepwise approach was used to analyse risk by relative and absolute risks, stratification analysis and the predispositional allele test. The strongest relative and absolute risks were observed for DQB1*02-DQA1*0501/DQB1*0302-DQA1*0301 heterozygotes (AR 1/46, P < 0.001) or the simultaneous presence of both DRB1*03 and DQB1*0302 (AR 1/52, P < 0.001). Stratification analysis showed that DQB1*0302 was more frequent among DRB1*04 patients than DRB1*04 controls (P < 0.001), while DRB1*03 was more frequent among both DQA1*0501 (P < 0.001) and DQB1*02 (P < 0.001) patients than respective controls. The predispositional allele test indicated that DRB1*03 (P < 0.001) would be the predominant risk factor on the DRB1*03-DQA1*0501-DQB1*02 haplotype. In contrast, although DQB1*0302 (P < 0.001) would be the predominant risk factor on the DRB1*04-DQA1*0301-DQB1*0302 haplotype, the predispositional allele test also showed that DRB1*0401, but no other DRB1*04 subtype, had an additive risk to that of DQB1*0302 (P < 0.002). It is concluded that the association between type 1 diabetes and HLA is due to a complex interaction between DR and DQ since (1) DRB1*03 was more strongly associated with the disease than DQA1*0501-DQB1*02 and (2) DRB1*0401 had an additive effect to DQB1*0302. The data from this population-based investigation suggest an independent role of DR in the risk of developing type 1 diabetes, perhaps by providing diseases-promoting transcomplementation molecules.     

Identification of a novel HLA-A allele (A*1115) in the UK National External Quality Assessment Schemes for Histocompatibility and Immunogenetics' Educational Cell Exchange

The novel allele, HLA-A*1115, was identified in an 'Educational Scheme' sample (ED03/03 - from a north-western European Caucasoid blood donor) distributed by the UK National External Quality Assessment Schemes for Histocompatibility and Immunogenetics. ED03/03 was typed by serology, the polymerase chain reaction using sequence-specific primers and sequence-based typing. A*1115 is most similar to A*110101 with a single mismatch (G to C) at constant position 565, leading to a conservative amino acid change from valine (GTG) to leucine (CTG) at codon 165 in the alpha(2) domain. This substitution has not been reported for any other HLA class I allele so far. The HLA-A*1115-bearing haplotype was B*350101; Cw*040101; DRB1*140101; DRB3*020201; DQA1*010401; DQB1*0503; DPA1*0103/07; DPB1*030101. Extensive serological typing indicated that this allele essentially encodes a 'normal' HLA-A11 specificity.