Analysis of HLA-DR and -DQ gene polymorphisms in Sudanese patients with type 1 (insulin-dependent) diabetes

Virus-induced diabetes mellitus: revisiting infection etiology in light of SARS-CoV-2

Diabetes mellitus (DM) is comprised of two predominant subtypes: type 1 diabetes mellitus (T1DM), accounting for approximately 5 % of cases worldwide and resulting from autoimmune destruction of insulin-producing β-cells, and type 2 (T2DM), accounting for approximately 95 % of cases globally and characterized by the inability of pancreatic β-cells to meet the demand for insulin due to a relative β-cell deficit in the setting of peripheral insulin resistance. Both types of DM involve derangement of glucose metabolism and are metabolic diseases generally considered to be initiated by a combination of genetic and environmental factors. Viruses have been reported to play a role as infectious etiological factors in the initiation of both types of DM in predisposed individuals. Among the reported viral infections causing DM in humans, the most studied include coxsackie B virus, cytomegalovirus and hepatitis C virus. The recent COVID-19 pandemic has highlighted the diabetogenic potential of SARS-CoV-2, rekindling interest in the field of virus-induced diabetes (VID). This review discusses the reported mechanisms of viral-induced DM, addressing emerging concepts in VID, as well as highlighting areas where knowledge is lacking, and further investigation is warranted.

The phenotype of type 1 diabetes in sub-Saharan Africa

The phenotype of type 1 diabetes in Africa, especially sub-Saharan Africa, is poorly understood. Most previously conducted studies have suggested that type 1 diabetes may have a different phenotype from the classical form of the disease described in western literature. Making an accurate diagnosis of type 1 diabetes in Africa is challenging, given the predominance of atypical diabetes forms and limited resources. The peak age of onset of type 1 diabetes in sub-Saharan Africa seems to occur after 18-20 years. Multiple studies have reported lower rates of islet autoantibodies ranging from 20 to 60% amongst people with type 1 diabetes in African populations, lower than that reported in other populations. Some studies have reported much higher levels of retained endogenous insulin secretion than in type 1 diabetes elsewhere, with lower rates of type 1 diabetes genetic susceptibility and HLA haplotypes. The HLA DR3 appears to be the most predominant HLA haplotype amongst people with type 1 diabetes in sub-Saharan Africa than the HLA DR4 haplotype. Some type 1 diabetes studies in sub-Saharan Africa have been limited by small sample sizes and diverse methods employed. Robust studies close to diabetes onset are sparse. Large prospective studies with well-standardized methodologies in people at or close to diabetes diagnosis in different population groups will be paramount to provide further insight into the phenotype of type 1 diabetes in sub-Saharan Africa.

Clinical features, biochemistry, and HLA-DRB1 status in youth-onset type 1 diabetes in Sudan

OBJECTIVE

To further understand clinical and biochemical features, and HLA-DRB1 genotypes, in new cases of diabetes in Sudanese children and adolescents.

RESEARCH DESIGN AND METHODS

Demographic characteristics, clinical information, and biochemical parameters (blood glucose, HbA1c, C-peptide, autoantibodies against glutamic acid decarboxylase 65 [GADA] and insulinoma-associated protein-2 [IA-2A], and HLA-DRB1) were assessed in 99 individuals <18 years, recently (<18 months) clinically diagnosed with T1D. HLA-DRB1 genotypes for 56 of these Arab individuals with T1D were compared to a mixed control group of 198 healthy Arab (75%) and African (25%) individuals without T1D.

RESULTS

Mean ± SD age at diagnosis was 10.1 ± 4.3 years (range 0.7-17.6 years) with mode at 9-12 years. A female preponderance was observed. Fifty-two individuals (55.3%) presented in diabetic ketoacidosis (DKA). Mean ± SD serum fasting C-peptide values were 0.22 ± 0.25 nmol/L (0.66±0.74 ng/ml). 31.3% were autoantibody negative, 53.4% were GADA positive, 27.2% were IA-2A positive, with 12.1% positive for both autoantibodies. Association analysis compared to 198 controls of similar ethnic origin revealed strong locus association with HLA-DRB1 (p < 2.4 × 10-14 ). Five HLA-DRB1 alleles exhibited significant T1D association: three alleles (DRB1*03:01, DRB1*04:02, and DRB1*04:05) were positively associated, while three (DRB1*10:01, DRB1*15:02, and DRB1*15:03) were protective. DRB1*03:01 had the strongest association (odds ratio = 5.04, p = 1.7 × 10-10 ).

CONCLUSIONS

Young Sudanese individuals with T1D generally have similar characteristics to reported European-origin T1D populations. However, they have higher rates of DKA and slightly lower autoantibody rates than reported European-origin populations, and a particularly strong association with HLA-DRB1*03:01.

Association of HLA-DRB1 and -DQB1 alleles with type 1 (autoimmune) diabetes in African Arabs: systematic review and meta-analysis

Several studies confirmed the association of HLA-DRB1 and -DQB1 alleles with altered risk of type 1 diabetes (T1D). However, data from individual studies based on small sample sizes yielded often conflicting findings in African Arabs. This is a systematic review and meta-analysis aimed at comprehensively evaluating this association with T1D, using molecular HLA data. Relevant studies were identified through systemic search of Medline/PubMed, Cochrane, Science Direct, ResearchGate, and EMBASE databases. Statistical analysis was carried out using RevMan, and Comprehensive Meta-analysis programs. Given the heterogeneity of African Arabs, we also performed subgroup analysis according to ethnicity. Analysis of sensitivity, heterogeneity, and publication bias were performed to validate the outcome of the findings. This meta-analysis included 862 T1DM cases, along with 1,390 normoglycemic control, and comprised ten comparisons. 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. This meta-analysis was characterized by low heterogeneity, sensitivity, and publication bias, indicating the robustness and reliability of the results.

BACKGROUND

Several studies confirmed the association of HLA-DRB1 and -DQB1 alleles with altered risk of type 1 diabetes (T1D). However, data from individual studies based on small sample sizes yielded often conflicting findings in African Arabs. This is a systematic review and meta-analysis aimed at comprehensively evaluating this association with T1D, using molecular HLA data.

METHODS

Relevant studies were identified through systemic search of Medline/PubMed, Cochrane, Science Direct, ResearchGate, and EMBASE databases. Statistical analysis was carried out using Revman, and Comprehensive Meta-analysis programs. Given the heterogeneity of African Arabs, we also performed subgroup analysis according to ethnicity. Analysis of sensitivity, heterogeneity, and pub¬lication bias were performed to validate the outcome of the findings. This meta-analysis included 862 T1DM cases, along with 1,390 normoglycemic control, and comprised ten comparisons.

RESULTS

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.

CONCLUSION

This meta-analysis was characterized by low heterogeneity, sensitivity, and publication bias, indicating the robustness and reliability of the results.

Association of HLA-DQA1 and -DQB1 alleles with type I diabetes in Arabs: a meta-analyses

This study aimed at assessing the nature and significance of associations between various alleles of HLA-DQA1, HLA-DQB1, and type I diabetes (T1D) in Arab populations. Evidence from literature (published before 20 April 2015) was amassed and analysed through multiple meta-analyses, which yielded effect summary odds ratios and 95% confidence intervals for 24 alleles and 4 haplotypes. A total of 1273 cases and 1747 controls from 16 studies were analysed. High levels of significance were obtained to support higher T1D risk when harbouring DQA1*03:01. The alleles DQB1*02:01 and *03:02 and the haplotypes DR3 and DR4 were significant risk factors, albeit with high publication heterogeneity. The protective effects of DQA1*01:01, DQB1*05:03, *06:02, *06:03, and *06:04 were robustly suggested by all indicators of meta-analyses. The haplotypes DR7 and DR11 were strongly suggested to be protective in Arabs. A relatively small number of studies have emerged from Arab countries, mostly with inadequate power on an individual basis. This study fills the gap by providing significant size effect of human leukocyte antigen (HLA) alleles and completes the continuum of global ethnic differences in this context.

A comparison of HLA-DR and -DQ allele and haplotype frequencies in Trinidadian populations of African, South Asian, and mixed ancestry

Using polymerase chain reaction-sequence-specific primer (PCR-SSP) typing, this study determined the frequency of human leukocyte antigen (HLA) DR- and -DQ alleles and haplotypes in individuals of African (n = 75), South Asian (n = 98), and mixed (n = 102) ancestry from the Caribbean island of Trinidad. We detected 19 different haplotypes containing DRB3, 8 containing DRB4, 6 containing DRB5, and 6 different haplotypes without DRB3/4/5 genes. Twenty-nine haplotypes were identified in Africans, 24 in the South Asians, and 32 in the mixed group. We detected significant differences between the populations, principally at the DQA1 and DQB1 loci, although the allele frequency for DRB1*0901 was highest in the Africans (p(c) < 0.05). Trinidad African and mixed groups were generally more diverse than the South Asians and displayed a wider range of DRB1-DQB1 associations; DQB1*02 and DQB1*0301 each associated with five to six different DRB1 alleles in the Africans and mixed group but only two in South Asians. In the Africans and the mixed group, DQB1*04 was found with DRB1*0302 and DRB1*04, but only with DRB1*08 in the South Asians. Trinidad Africans revealed consistencies with populations in Western, Central, and Northern Africa, but differed considerably from individual populations on the African continent. Trinidad South Asians displayed similar allele frequencies and associations to other populations from Northern India.

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.

HLA class II allele and haplotype frequencies in Ethiopian Amhara and Oromo populations

HLA class II alleles were identified in 181 healthy unrelated Ethiopian children of both sexes and in 350 European controls from the South of France. The Ethiopian individuals belonged to the two major ethnic groups of the country: Oromo (N=83) and Amhara (N=98). In both panels, genetic polymorphism of HLA class II alleles was analysed for the first time by molecular typing of DRB1, DQA1 and DQB1 loci. Allelic and phenotypic frequencies were compared with those of European controls and other African populations. Construction of HLA class II three-locus haplotypes was also performed. The study revealed some differences between the two groups. Characteristic features of Central and North African populations appeared on the Ethiopian HLA genotypes. Surprisingly, DRB1*11 presented one of the lowest gene frequencies in both Ethiopian ethnic groups in contrast to Europeans and West Africans. Furthermore, this decrease was more marked than those observed using serological techniques in other geographically close East African countries. Oromo and Amhara only showed minor differences in spite of their different origins and histories. One significant difference consisted of a lower DRB1*01 gene frequency in Oromo as reported in most West African people. Some new or rare haplotypes were also observed in the Oromo group. Our results underline the distinctive features of the Ethiopian populations among the few HLA genotyping data available for East African groups and emphasise the major interest of such investigations in this region of Africa.

Population analysis of protection by HLA-DR and DQ genes from insulin-dependent diabetes mellitus in Swedish children with insulin-dependent diabetes and controls

A negative association between insulin-dependent diabetes mellitus (IDDM) and HLA-DR, DQA1 or DQB1 was found in a large population-based investigation of childhood-onset patients (more than 420 patients) and controls (more than 340 controls) from Sweden. The relative risk was decreased for several haplotypes that were negatively associated with IDDM: DR15-DQA1*0102-DQB1*0602, DR7-DQA1*0201-DQB1*0303, DR14-DQA1*0101-DQB1*0503, DR11-DQA1*0501-DQB1*0301, DR13-DQA1*0103-DQB1*0603 and DR4-DQA1*0301-DQB1*0301. In a relative predispositional effect (RPE) analysis, however, only the DR15-DQA1*0102-DQB1*0602 haplotype was significantly decreased, which suggests that the major protective effect for IDDM is carried by this haplotype. This was supported by the observation that all genotypes which were negatively associated with IDDM, except DR7/13, included at least one allele from the DR15-DQA1*0102-DQB1*0602 haplotype. Relative predispositional effect (RPE) analysis of genotypes showed further that the DR15-DQA1*0102-DQB1*0602 haplotype was also negatively associated with IDDM when combined with any other haplotype, whether negatively or positively associated with IDDM. This supports previous suggestions that DR15-DQA1*0102-DQB1*0602 acts dominantly. However, both the stratification and the predispositional allele test failed to distinguish the negative association between IDDM and DR15 from that of DQB1*0602. On the other hand, these tests indicated that DQA1*0102 was not likely to explain the negative association between IDDM and the DR15-DQA1*0102-DQB1*0602 haplotype. We conclude that the major protective effect for IDDM in the population of Swedish children is conferred by the DR15-DQA1*0102-DQB1*0602 haplotype in a dominant fashion, the DQB1*0602 allele being the allele most likely to be responsible for the protective effect of this haplotype, although an effect of the DR15 allele could not be excluded.

The presence of the HLA class II allele DPB1*0501 in ethnic Thais correlates with an enhanced vaccine-induced antibody response to a malaria sporozoite antigen

In this study, we examined the correlation between the frequency of allelic variants of the class II human leukocyte antigen (HLA) DR, DQ and DP gene loci and the quantitative humoral immune response observed in 71 Thai volunteers, subsequent to vaccination with a conjugated subunit vaccine. This vaccine was designed to induce antibodies directed against the immunodominant repeat region of the Plasmodium falciparum circumsporozoite (CS) protein. The presence of the DPB1*0501, a relatively common allele in Asian populations, was found to be associated with high vaccine-induced CS repeat-specific antibody responses in the volunteers. Given the increasing focus on the use of subunit vaccines in the control of infectious diseases, consideration of the influence of class II allele frequencies in ethnically diverse recipient populations may be important.

Prevalence of islet cell and thyrogastric autoantibodies in Sudanese patients with type 1 diabetes

In this study, sera from 96 Sudanese patients with Type 1 diabetes and from 86 matched controls were tested for the following organ-specific antibodies: islet cell antibodies (ICA), thyroid microsomal antibodies (TMA), antithyroglobulin antibodies (ATA), and gastric parietal cell antibodies (PCA). In diabetic patients the prevalence rates of these antibodies were: ICA = 41.7%, ATA = 2.0%, TMA = 7.3%, PCA = 6.3%. All these rates were significantly higher than in controls except for ATA which showed similar low prevalence rates in patients and controls. The pattern of prevalence of these antibodies by age, sex, and duration of diabetes was assessed and compared with reports from other populations. The general pattern of these antibodies is similar to that reported in Caucasian populations, except for a slightly greater tendency for ICA to persist with increased duration of diabetes in our sample. Furthermore, the low prevalence of TMA in our population is comparable to that reported in Black American diabetic patients but significantly lower than rates reported in certain other racial groups.

Association of insulin-dependent diabetes mellitus in Taiwan with HLA class II DQB1 and DRB1 alleles

The allelic constitution at HLA class II DRB1, DQB1, DQA1, and DPB1 loci of IDDM patients from Taiwan was compared with that of ethnically matched nondiabetic individuals by PCR-based DNA typing. Of the three haplotypes found to be positively associated with IDDM in Taiwan, two (DRB1*0301-DQA1*0501-DQB1*0201 and DR4-DQA1*0301-DQB1*0302) appear to be identical to the susceptible haplotypes in Caucasian and black populations, whereas the third haplotype (DR4-DQA1*0301-DQB1*04) has been reported to be positively associated with IDDM only in the Japanese population. The three haplotypes, DRB1*1502-DQA1*0102-DQB1*0601 and DRB1*1201 (or 1202)-DQA1*0501-DQB1*0301 and DRB1*0803-DQA1*0103-DQB1*0601, were negatively associated with IDDM in Taiwan; a protective effect of the last haplotype has not been reported previously. Neither DQ beta non-Asp-57 nor DQA1*0301 alone appears sufficient to account for the HLA-associated susceptibility to IDDM in Taiwan. Also, the DQ alpha beta heterodimer encoded by the alleles DQA1*0301/DQB1*0201, DQA1*0301/DQB1*0302, or DQA1*0501/DQB1*0201 does not explain the susceptibility of a larger fraction of the IDDM patients than the residue at position 57 of the DQ beta chain or DQA1*0301. Finally, the DRB1 alleles appear to affect IDDM susceptibility, although for most haplotypes the effect of individual loci cannot be assessed due to the linkage disequilibrium between the DQ and the DR region.

HLA-DR and -DQ genotypes of celiac disease patients serologically typed to be non-DR3 or non-DR5/7

The susceptibility to develop celiac disease (CD) seems to be primarily associated to a particular HLA-DQ alpha/beta heterodimer encoded by the DQA1*0501 and DQB1*0201 alleles, in cis position on the DR3-DQ2 haplotype or in trans position by DR5-DQ7/DR7-DQ2 heterozygotes. However, exceptional patients exist who are neither DR3 nor DR5/DR7, particularly among Southern European populations. We therefore examined the DRB1, DQA1, and DQB1 alleles of 13 Spanish CD patients who were serologically typed to be neither DR3 nor DR5/DR7. Five patients were found to carry the DQA1*0501 and DQB1*0201 alleles either in cis or in trans position, three of them had previously been serologically mistyped. However, two of these patients carried DQA1*0501 and DQB1*0201 on haplotypes other than DR3 or DR5 in combination with DR7. One of the latter patients carried an unusual DR4-DQ2 haplotype, while another had an unusual DR8-DQ2 haplotype. Four of the remaining eight patients carried DR4-DQ8 haplotypes. Taken together, our findings provide further evidence that the DQ alpha/beta heterodimer encoded by the DQA1*0501 and the DQB1*0201 alleles confers the primary HLA-associated susceptibility to develop CD. However, our studies also corroborate that a second (and "weaker") HLA-associated CD susceptibility gene may be present on some DR4-carrying haplotypes.

Distribution of HLA-DQA1, -DQB1 and DRB1 alleles in black IDDM patients and controls from Zimbabwe

We have used the XI Histocompatibility Workshop sequence-specific oligonucleotide probes to determine the DRB1, DQA1 and DQB1 genotypes by dot-blot hybridization of polymerase chain reaction (pcr)-amplified material from a homogenous black population in Zimbabwe. The DR4 subtype DRB1*0405, the DR3 subtype DRB1*0301, DQB1*0201 and DQB1*0302 and DQA1*0301 and DQA1*0501 were significantly increased in the IDDM group compared to the controls, whereas DRB1*11, DQB1*0602 and DQA1*0102 were significantly decreased. Taken together, the data show that susceptibility and resistance to IDDM are associated both with particular haplotypes and DQA1-DQB1 heterodimers without one or other being overriding.

HLA-DP polymorphism in Sudanese controls and patients with insulin-dependent diabetes mellitus

Human leukocyte antigen (HLA) genes are candidates for susceptibility to insulin-dependent diabetes mellitus (IDDM). The association of IDDM with particular DR and DQ alleles has been reported in all populations studied, but its association with HLA-DP alleles has been controversial. To address this question we analyzed 19 DPB1 and 2 DPA1 alleles and their associations in well-characterized Sudanese (an admixture of Arab and Black) IDDM patients (n = 71) and ethnically matched controls (n = 86) using polymerase chain reaction-sequence specific oligonucleotide (PCR-SSO) typing. There were no significant differences between the patient and control groups in the DPB1 frequencies. DPB1*0201, *0401 and DPA1*01 were the most frequent alleles in both IDDM patients and control subjects. Significant positive and negative associations between DPB1 and DPA1 alleles were detected in both groups. A novel DPB1 allele included in DPB1*1701 was identified.