Among 52 participants whose human leukocyte antigen typing was carried out, all of the participants with slowly progressive insulin-dependent diabetes mellitus who had DRB1*09:01 were positive by GADA-ELISA (P = 0.021).
Negative associations were found between T1D and DRB1*07, *11, *13, and *15 (13.8% vs 26.1% in controls [P<sub>c</sub> = 0.00175], 3.9% vs 16.9% in controls [P<sub>c</sub> = 6.55× 10<sup>-6</sup> ], 5.5% vs 21.6% in controls [P<sub>c</sub> = 2.51 × 10<sup>-7</sup> ], and 16.9% vs 43.9% in controls [P<sub>c</sub> = 9.94× 10<sup>-10</sup> ], respectively).
In T1D patients, the allele DRB1*03:01 demonstrated highly significant T1D association (p < 10<sup>-16</sup>), with no apparent risk conferred by DRB1*04:xx alleles.
Our study indicates that DRB1*03 (OR = 2.86), DRB1*04 (OR = 2.78), and DQB1*02 (OR = 2.29), are positively associated with increased risk of T1DM, while DRB1*07 (OR = 0.48), DRB1*11 (OR = 0.20), DRB1*13 (OR = 0.47), DRB1*15 (OR = 0.30), DQB1*05 (OR = 0.39), and DQB1*06 (OR = 0.27) were negatively associated with T1D, suggesting a protective role against T1D.
A strong positive association of DRB1*04-DQA1*0301-DQBl*0302 (OR=5.67, p<0.001) and DRB1*0301-DQA1*0501-DQB1*0201 (OR=6.24, p<0.001) putative haplotypes with IDDM was evident in Jordanian IDDM patients whereas DRB1*1101-DQA1*0505- DQB1*0301 (OR=0.23, p=0.03) was shown to have a protective role against T1D in Jordanians.
We generated a novel HLA-transgenic mouse model that expresses high-risk genes for type 1 diabetes (DRB1*03:01-DQA1*05:01-DQB1*02:01) as well as human CD80 under the rat insulin promoter and human CD4, on a C57BL/6 background.
Analysis of HLA-DRB1 genotypes revealed locus-level T1D association (p = 6.0E-05); DRB1*04:01 appeared predisposing (p < 3.0E-06), and DRB1*14:01 appeared protective (p = 1.7E-02).
Human leukocyte antigen typing showed haplotype DRB1*09:01-DQB1*03:03, which was reported to be closely associated with type 1 diabetes mellitus in Japan.
The higher frequency of HLA-DRB1*03/DRB1*03 among APS3v patients was the only significant difference in genotype frequency when compared to T1D patients, while high risk (HLA-DRB1*03/DRB1*04) and medium risk genotypes for T1D (HLA-DRB1*04/DRB1*04) occurred with similar frequencies in both patient groups.
HLA Class II genotyping revealed DRB1-DQB1*0901-*0303, a common susceptibility haplotype in Japanese patients with type 3 APS or acute-onset type 1 diabetes.
DRB1*04:01-restricted responses toward many of these peptides have been previously described, but responses to a novel pre-proinsulin 9-28 peptide were commonly observed in subjects with T1D.
In addition to clarifying the roles of several known T1D HLA alleles and haplotypes, we discovered that the DRB1*08:03-DQB1*06:01 haplotype is protective against T1D.
The patients with coexisting T1D and CeD had an intermediate carrier frequency (72.8%) of the DRB1 *03:01- DQB1 *02:01- DQA1 *05:01 haplotype compared to T1D (64.1%) and CeD (88.7%) patients.
Among the strongest T1D HLA associations, stands out, as susceptible, the alleles DRB1*04:05 (OR = 7.3), DQB1*03:02 (OR = 6.1) and DQA1*03:03 (OR = 4.5), as well as the haplotypes DRB1*04:05-DQA1*03:03-DQB1*03:02 (OR = 100.9) and DRB1*04:04-DQA1*03:01-DQB1*03:02 (OR = 22.1), and DQB1*06:02 (OR = 0.07) and DRB1*15:01-DQA1*01:02-DQB1*06:02 (OR = 0.04) as protective.
In Somali children with T1D aged 13.5 ± 5 yr (35% female, disease duration 6.5 ± 3.6 yr), the most common HLA allele was DRB1*03:01 (93%, compared with 45% of Somali controls), followed by DRB1*13:02 (27%).
The summary effect of haplotypes was generally seen in genotypes, while the expected synergistic effect of DR3-DQ2 and DR4-DQ8 (DRB1*04:03 excluded) combination was also clear in the T1D risk association analysis.
The strongly associated T1D haplotype DRB1*0301-DQA1*05-DQB1*0201 is also associated with LADA but confers only half of the T1D risk (odds ratio 2.65 vs 4.84).
DRB4*01:03:01 was strongly associated with type 1 diabetes (P = 10(-36)), yet its association was extensively affected by DRB1 alleles from protective (DRB1*04:03:01) to high (DRB1*04:01:01) risk, but its association with DRB1*04:05:01 decreased the risk.
We also confirm that genetic susceptibility to T1D is associated with the DRB1*03:01-DQA1*05:01-DQB1*02:01 and DRB1*04-DQA1*03:01-DQB1*03:02 haplotypes in Brazilian northeast region.