Association of HLA-DR-DQ polymorphisms with diabetes in Tunisian patients

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.

Association between alleles, haplotypes, and amino acid variations in HLA class II genes and type 1 diabetes in Kuwaiti children

Type 1 diabetes (T1D) is a complex autoimmune disorder that is highly prevalent globally. The interactions between genetic and environmental factors may trigger T1D in susceptible individuals. HLA genes play a significant role in T1D pathogenesis, and specific haplotypes are associated with an increased risk of developing the disease. Identifying risk haplotypes can greatly improve the genetic scoring for early diagnosis of T1D in difficult to rank subgroups. This study employed next-generation sequencing to evaluate the association between HLA class II alleles, haplotypes, and amino acids and T1D, by recruiting 95 children with T1D and 150 controls in the Kuwaiti population. Significant associations were identified for alleles at the HLA-DRB1, HLA-DQA1, and HLA-DQB1 loci, including DRB1*03:01:01, DQA1*05:01:01, and DQB1*02:01:01, which conferred high risk, and DRB1*11:04:01, DQA1*05:05:01, and DQB1*03:01:01, which were protective. The DRB1*03:01:01~DQA1*05:01:01~DQB1*02:01:01 haplotype was most strongly associated with the risk of developing T1D, while DRB1*11:04-DQA1*05:05-DQB1*03:01 was the only haplotype that rendered protection against T1D. We also identified 66 amino acid positions across the HLA-DRB1, HLA-DQA1, and HLA-DQB1 genes that were significantly associated with T1D, including novel associations. These results validate and extend our knowledge on the associations between HLA genes and T1D in Kuwaiti children. The identified risk alleles, haplotypes, and amino acid variations may influence disease development through effects on HLA structure and function and may allow early intervention via population-based screening efforts.

Frequency of auto-antibodies of type 1 diabetes in adult patients with celiac disease

Both celiac disease (CD) and type 1 diabetes (T1D) are autoimmune diseases resulting from a complex interplay between genetic susceptibility and environmental factors.

Association of HLA-DR-DQ alleles, haplotypes, and diplotypes with type 1 diabetes in Saudis

AIMS

Type 1 diabetes (T1D) is an autoimmune disease that affects many children worldwide. Genetic factors and environmental triggers play crucial interacting roles in the aetiology. This study aimed to assess the contribution of HLA-DRB1-DQA1-DQB1 alleles, haplotypes, and genotypes to the risk of T1D among Saudis.

METHODS

A total of 222 children with T1D and 342 controls were genotyped for HLA-DRB1, -DQA1, and -DQB1 using reverse sequence-specific oligonucleotide (rSSO) Lab Type high definition (HD) kits. Alleles, haplotypes, and diplotypes were compared between cases and controls using the SAS statistical package.

RESULTS

DRB1*03:01-DQA1*05:01-DQB1*02:01 (32.4%; OR = 3.68; P_c < .0001), DRB1*04:05-DQA1*03:02-DQB1*03:02 (6.6%; OR = 6.76; P_c < .0001), DRB1*04:02-DQA1*03:01-DQB1*03:02 (6.0%; OR = 3.10; P_c = .0194), DRB1*04:01-DQA1*03:01-DQB1*03:02 (3.7%; OR = 4.22; P_c = .0335), and DRB1*04:05-DQA1*03:02-DQB1*02:02 (2.7%; OR = 6.31; P_c = .0326) haplotypes were significantly increased in cases compared to controls, whereas DRB1*07:01-DQA1*02:01-DQB1*02:02 (OR = 0.41; P_c = .0001), DRB1*13:01-DQA1*01:03-DQB1*06:03 (OR = 0.05; P_c < .0001), DRB1*15:01-DQA1*01:02-DQB1*06:02 (OR = 0.03; P_c < .0001), and DRB1*11:01-DQA1*05:05-DQB1*03:01 (OR = 0.07; P_c = .0291) were significantly decreased. Homozygous DRB1*03:01-DQA1*05:01-DQB1*02:01 genotypes and combinations of DRB1*03:01-DQA1*05:01-DQB1*02:01 with DRB1*04:05-DQA1*03:02-DQB1*03:02, DRB1*04:02-DQA1*03:01-DQB1*03:02, and DRB1*04:01-DQA1*03:01-DQB1*03:02 were significantly increased in cases than controls. Combinations of DRB1*03:01-DQA1*05:01-DQB1*02:01 with DRB1*07:01-DQA1*02:01-DQB1*02:02 and DRB1*13:02-DQA1*01:02-DQB1*06:04 showed low OR values but did not remain significantly decreased after Bonferroni correction.

CONCLUSIONS

HLA-DRB1-DQA1-DQB1 alleles, haplotypes, and diplotypes in Saudis with T1D are not markedly different from those observed in Western and Middle-Eastern populations but are quite different than those of East Asians.

Immunogenetic Study of Diabetes Mellitus in Relation to HLA DQ and DR

INTRODUCTION

Type-1 diabetes mellitus (T1DM) which is also known as insulin-dependent diabetes is diagnosed mainly during childhood and accounts for approximately 5%-10% of all cases of DM. In India, early onset diabetes (<15 years age) constitutes about 1%-4% of the total diabetic population. The insulitis as well as to a humoral (B cell) response with production of antibodies to IAA, GAD, and the protein tyrosine phosphatase IA2 (IA-2AA) is the main pathogenesis of T1DM. Human leukocyte antigen (HLA)-DR and DQ contributes approximately 40%-50% of the inherited susceptibility for T1DM and most frequently involved haplotypes are DRB1*0301-DQB1*0201, DRB1*0301-DQA1*0501-DQB1*0201, and DRB1*0401-DQB1*0302.

METHOD AND MATERIAL

Total 70 cases of DM in age group of 10 years to 65 years and 25 healthy controls of same age group 30 cases of complicated diabetic mellitus were included in the study. 2 mL blood was taken in an EDTA vial for HLA typing and 5 mL blood was taken in a plain vial for anti-GAD antibody. HLA DQB1 and DRB1 were done by sequence specific priming polymerase chain reaction method. Indirect immunofluorescent test was used for anti-GAD antibody. Statistical analysis was performed using SPSS version-16.

RESULTS

Total 40.9% cases of type-I DM were found seropositive for anti-GAD antibody. None of the cases of type-II DM was anti-GAD antibody positive. HLA DRB1*03010 were significantly more in diabetic patient (P < 0.011) as compared to control. DRB1*O403/6 shows that a relative risk of 1.08 was slightly more frequent in DM cases as compared to the control. DQB1*0201 was significantly high (P < 0.004) in DM patient as compared to control with a relative risk of 1.68. Correlation of DR, DQ antigen with types of DM showed that in type-I DM, DRB1*03010 was significantly high (P = 0.009) with a relative risk of 2.78 as compared type-II DM. In DQ typing, DQB1*0201 was significantly high in type-I DM in comparison to type-II DM (65% vs. 30%, P = 0.026, RR = 2.05). Comparison of DQB1 in type-I DM with healthy control showed that DQB1*0201 was significantly high in type-I DM as compared to healthy control (P = 0.0003, RR = 3.09). In type-I DM patient's homozygosity at DRB1*03010, DRB1*03010 was significantly high as compared to the control (P < 0.047, RR = 2.33). Correlation of anti-GAD antibody with DRB1 and DQB1 showed that 77.7% anti-GAD antibody positive cases were DRB1*03010 positive. Similarly, in DQB1 typing, 66.6% anti-GAD positive cases have DQB1*0201.

CONCLUSION

Prevalence of anti-GAD antibody in Indian population was found up to 45%. HLA DRB1*3010 and HLA DQB1*0201 were the most susceptible haplotypes for type-I DM. HLA DRB1*14 and HLA DRB1*15 were the protective haplotypes for type-I DM. Susceptibility to type-I DM increases when the homozygosity for DRB1*03010 was present. Diagnosis of type-I DM by anti-GAD antibody was possible in only 40.9% cases but if DRB1 and DQB1 typing is added in the diagnosis then diagnostic efficacy increases up to 83%.

Diverse human leukocyte antigen association of type 1 diabetes in north India

BACKGROUND

Type 1 diabetes (T1D) is a complex disease, with involvement of various susceptibility genes. Human leukocyte antigen (HLA) on chromosome 6p21 is major susceptibility region. This study examined genetic association of HLA genes with T1D.

METHODS

The study recruited 259 T1D patients and 706 controls from north India. PCR-SSP and LiPA were used to type HLA Class I and II alleles.

RESULTS

At HLA Class I locus, HLA-A*02, A*26, B*08 and B*50 were significantly increased in patients vs controls (39.8% vs 28.9% [Bonferroni-corrected P {P_c } = 0.032], 24.7% vs 9.6% [P_c  = 4.83 × 10^-8 ], 37.2% vs 15.7% [P_c  = 1.92 × 10^-9 ], and 19.4% vs 5.5% [P_c  = 4.62 × 10^-9 ], respectively). Similarly, in Class II region, DRB1*03 showed a strong positive association with T1D (78.7% vs 17.5% in controls; P = 1.02 × 10^-9 ). Association of DRB1*04 with T1D (28.3% vs 15.5% in controls; P_c  = 3.86 × 10^-4 ) was not independent of DRB1*03. Negative associations were found between T1D and DRB1*07, *11, *13, and *15 (13.8% vs 26.1% in controls [P_c  = 0.00175], 3.9% vs 16.9% in controls [P_c  = 6.55× 10^-6 ], 5.5% vs 21.6% in controls [P_c  = 2.51 × 10^-7 ], and 16.9% vs 43.9% in controls [P_c  = 9.94× 10^-10 ], respectively). Compared with controls, patients had significantly higher haplotype frequencies of A*26-B*08-DRB1*03-DQA1*05-DQB1*02 (10.43% vs 1.96%; P = 7.62 × 10^-11 ), A*02-B*50-DRB1*03-DQA1*05-DQB1*02 (6.1% vs 0.71%; P = 2.19 × 10^-10 ), A*24-B*08-DRB1*03-DQA1*05-DQB1*02 (4.72% vs 0.8%; P = 5.4 × 10^-7 ), A*02-B*08-DRB1*03-DQA1*05-DQB1*02 (2.36% vs 0.18%; P = 3.6 × 10^-5 ), and A*33-B*58-DRB1*03-DQA1*05-DQB1*02 (4.33% vs 1.25%; P = 0.00019).

CONCLUSIONS

In north India, T1D is independently associated only with HLA-DRB1*03 haplotypes, and is negatively associated with DRB1*07, *11, *13, and *15.

Genetic meta-analysis of diagnosed Alzheimer's disease identifies new risk loci and implicates Aβ, tau, immunity and lipid processing

Risk for late-onset Alzheimer's disease (LOAD), the most prevalent dementia, is partially driven by genetics. To identify LOAD risk loci, we performed a large genome-wide association meta-analysis of clinically diagnosed LOAD (94,437 individuals). We confirm 20 previous LOAD risk loci and identify five new genome-wide loci (IQCK, ACE, ADAM10, ADAMTS1, and WWOX), two of which (ADAM10, ACE) were identified in a recent genome-wide association (GWAS)-by-familial-proxy of Alzheimer's or dementia. Fine-mapping of the human leukocyte antigen (HLA) region confirms the neurological and immune-mediated disease haplotype HLA-DR15 as a risk factor for LOAD. Pathway analysis implicates immunity, lipid metabolism, tau binding proteins, and amyloid precursor protein (APP) metabolism, showing that genetic variants affecting APP and Aβ processing are associated not only with early-onset autosomal dominant Alzheimer's disease but also with LOAD. Analyses of risk genes and pathways show enrichment for rare variants (P = 1.32 × 10-7), indicating that additional rare variants remain to be identified. We also identify important genetic correlations between LOAD and traits such as family history of dementia and education.

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.

Is HLA the cause of the high incidence of type 1 diabetes in the Canary Islands? Results from the Type 1 Diabetes Genetics Consortium (T1DGC)

INTRODUCTION

Incidence of childhood-onset type 1 diabetes mellitus in the Canary Islands is the highest reported so far in Spain, and among the highest worldwide. The HLA region accounts for approximately half the genetic risk of type 1 diabetes. Our aim was to assess distribution of high-risk and protective HLA haplotypes in the Canarian families included in the T1DGC, as compared to the rest of Spain.

METHODS

The T1DGC study, an international project to study the genetics and pathogenesis of type 1 diabetes, enrolled more than 3000 families with type 1 diabetes worldwide. Spain provided 149 of these families, of whom 42 were from Tenerife and Gran Canaria. HLA was genotyped centrally using a PCR-based, sequence-specific oligonucleotide probe system. Haplotypes were reconstructed using the deterministic algorithm alleHap in the R programming environment. Based on prior T1DGC results in Caucasian population, haplotypes DRB1*0405-DQA1*0301-DQB1*0302, DRB1*0401-DQA1*0301-DQB1*0302, DRB1*0301-DQA1*0501-DQB1*0201, DRB1*0402-DQA1*0301-DQB1*0302 and DRB1*0404-DQA1*0301-DQB1*0302 were considered high-risk. DRB1*0701-DQA1*0201-DQB1*0303, DRB1*1401-DQA1*0101-DQB1*0503, DRB1*1501-DQA1*0102-DQB1*0602, DRB1*1101-DQA1*0501-DQB1*0301, DRB1*1104-DQA1*0501-DQB1*0301, DRB1*1303-DQA1*0501-DQB1*0301, DRB1*1301-DQA1*0103-DQB1*0603 and DRB1*0403-DQA1*0301-DQB1*0302 were considered protective. The distribution of protective, high-risk, and other haplotypes in the (first two) affected siblings and unaffected parents from Canarian and non-Canarian Spanish families was compared (Chi-square test).

RESULTS

No significant differences were found between the regions in distribution of the HLA haplotypes in the affected siblings or in the non-affected parents.

CONCLUSIONS

The high incidence of childhood-onset type 1 diabetes in the Canarian population does not appear to be explained by a greater prevalence of high-risk class II HLA haplotypes in families with the disease. However, sample size limits the differences that can be detected in this study.

Anthropological analysis of Tunisian populations as inferred from HLA class I and class II genetic diversity: A meta-analysis

Despite their importance, anthropological meta-analyses which allow for comprehensive evaluation of the relationships of a given population were rare. This meta-analysis evaluates the origin of Tunisians using polymorphic profile of HLA class I (A, B), and class II (DRB1, DQB1) genes, in historical, social and cultural context, and is the only analysis in the Middle East-North Africa (MENA) region. A total of 20 eligible populations were selected from several databases, and included representing 2553 Tunisian individuals, who were compared with Mediterranean and sub-Saharan populations. In total, 204 HLA alleles were detected in Tunisians, which comprised 54 HLA-A, 76 HLA-B, 50 DRB1, and 24 DQB1 alleles. The most frequent alleles were A*02:01(24.72%) in Berbers of Zrawa, B*50:01 (13.90.11%) in Tunisian-So, DRB1*07:01 (28.66%) in Ghannouchians, and DQB1*02:01 (42.79%) in Tunisians-H. The A, B, DRB, and DQB1 genotypes of 420 individuals were further subjected to a selection study. Despite the relatively large sample size, the loci depicted non-significant negative Fnd values, an indication of overall trend to balancing selection or gene flow. Except for Berbers of Djerba, dendrograms, correspondence analyses, genetic distances and haplotype analysis demonstrated the close relatedness of Berbers, Southern and Northern Tunisians, and strong relatedness was evident to Western Mediterranean, North African and Iberian populations, but not Sub-Saharans and Eastern Mediterranean populations, including Arabs. Collectively, this suggests that the contribution of Arabs and sub-Saharans to the present Tunisian gene pool is low. In addition, all Mediterranean populations depict a typical Mediterranean substratum, except for Greeks.

The long and winding road to IgA deficiency: causes and consequences

INTRODUCTION

The most common humoral immunodeficiency is IgA deficiency. One of the first papers addressing the cellular and molecular mechanisms underlying IgA deficiency indicated that immature IgA-positive B-lymphocytes are present in these patients. This suggests that the genetic background for IgA is still intact and that class switching can take place. At this moment, it cannot be ruled out that genetic as well as environmental factors are involved. Areas covered: A clinical presentation, the biological functions of IgA, and the management of IgA deficiency are reviewed. In some IgA deficient patients, a relationship with a loss-of-function mutation in the TACI (transmembrane activator and calcium-modulating cyclophilin ligand interaction) gene has been found. Many other genes also have been associated. Gut microbiota are an important environmental trigger for IgA synthesis. Expert commentary: Expression of IgA deficiency is due to both genetic and environmental factors and a role for gut microbiota cannot be excluded.

The relationships between HLA class II alleles and antigens with gestational diabetes mellitus: A meta-analysis

Gestational diabetes mellitus (GDM) is defined as glucose intolerance with onset or first recognition during pregnancy. It is associated with an increased risk of pregnancy complications. Susceptibility to GDM is partly determined by genetics and linked with type 1 diabetes-associated high risk HLA class II genes. However, the evidence for this relationship is still highly controversial. In this study, we assessed the relationship between HLA class II variants and GDM. We performed meta-analysis on all of literatures available in PubMed, Embase, Web of Science and China National Knowledge Infrastructure databases. The odds ratio and 95% confidence interval of each variant were estimated. All statistical analyses were conducted using the Comprehensive Meta Analysis 2.2.064 software. At the allelic analysis, DQB1*02, DQB1*0203, DQB1*0402, DQB1*0602, DRB1*03, DRB1*0301 and DRB1*1302 reached a nominal level of significance, and only DQB1*02, DQB1*0602 and DRB1*1302 were statistically significant after Bonferroni correction. At the serological analysis, none of DQ2, DQ6, DR13 and DR17 was statistically significant following Bonferroni correction although they reached a nominal level of significance. In sum, our meta-analysis demonstrated that there were the associations between HLA class II variants and GDM but more studies are required to elucidate how these variants contribute to GDM susceptibility.

Prevalence of Autoantibodies and HLA DR, DQ in Type 1 Diabetes Mellitus

INTRODUCTION

Type I diabetes Mellitus (T1DM) is caused by autoimmune destruction of β-cells of pancreas. Two forms of T1DM are known called as 1A (autoimmune) and 1B (idiopathic).

AIM

Aim was to study the prevalence of Anti-TTG IgA, Anti-TPO, GADA, ZnT8 and IA-2 autoantibodies and HLA DR and DQ genes and its diagnostic value in T1DM.

MATERIALS AND METHODS

Thirty four T1DM patients, 59 type 2 diabetes mellitus (T2DM) patients and 28 healthy controls were included in study. Antibodies levels were estimated by ELISA and HLA typing was performed by SSP-PCR method.

RESULT

The prevalence of various autoantibodies in T1DM were Anti-TTG 14.7%, Anti-TPO 17.65%, GADA 38.23%, ZnT8 11.76% and IA-2 5.88%. Only GADA and ZnT8 were significantly positive in T1DM. GADA (66.67%) and ZnT8 (33.33%) positivity was more in patients below 15 years age while levels of other antibodies were higher after 15 years age. All autoantibodies were detected in higher frequency in T1DM than in T2DM and controls. HLA DR and DQ typing showed highly significant increase in DRB1*0301 (61.76%, p=0.00) and DQB1*0201 (64.71%, p=0.00) in T1DM. Subjects with HLA DRB1*0301 and DQB1*0201 had 80-100% positive prevalence of GADA, ZnT8, IA-2, Anti-TTG and Anti-TPO autoantibodies.

CONCLUSION

Combination of GADA antibody with DRB1 and DQB1 estimation improved diagnosis of T1A than insulin antigen specific antibodies alone.

Genetic Epidemiology of Type 1 Diabetes in the 22 Arab Countries

Type 1 diabetes (T1D) is a complex autoimmune disorder that results from the T cell-mediated destruction of the pancreatic β cells and is due to interactions between environmental and genetic factors. Although Arabs have one of the highest global incidence and prevalence rates of T1D, unfortunately, there is a dearth of information regarding the genetic epidemiology of T1D in the Arab world. Arabs share several HLA haplotypes with other ethnic groups, which confer either susceptibility or protection to T1D, but they have specific haplotypes that are distinctive from other ethnicities. Among different Arab countries, several non-HLA genes were reported to be associated with susceptibility to T1D, including CTLA4, CD28, PTPN22, TCRβ, CD3z, IL15, BANK1, and ZAP70. In Arab countries, consanguinity, endogamy, and first-cousin marriage rates are some of the highest reported worldwide and are responsible for the creation of several inbreeding communities within the Arab world that have led to an increase in homozygosity of both the HLA haplotypes and non-HLA genes associated with either protection or susceptibility to T1D among Arabs. Homozygosity reduces the HLA complexity and is expected to facilitate our understanding of the mode of inheritance of HLA haplotypes and provide valuable insight into the intricate genotype-phenotype correlations in T1D patients. In this review, based on literature studies, I will discuss the current epidemiological profile and molecular genetic risks of Arabs with T1D.

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.

The profile of HLA-DRB1 alleles in Arabs with type 1 diabetes; meta-analyses

Genes from the HLA complex have a major contribution in type 1 diabetes (T1D), which results from an interplay between environmental and genetic factors. The latter can explain some of the geographic variability in T1D occurrence around the world. Of a particular importance in this regard are the HLA-DR, -DP and -DQ loci. Consequently, we aimed at elucidating the collective genetic profiles of various alleles relating to HLA-DRB1 and -DP in T1D patients throughout the Arab World using the tools of meta-analysis. As for HLA-DQA1 and DQB1 alleles; this analysis was completed and published previously (see Introduction). As a result of limited availability of relevant studies of the HLA-DP locus, only HLA-DRB1 alleles were tackled in this paper. Our study showed that significant increases in T1D risk resulted from harboring the alleles DRB1*03:01 and *04:05 (odds ratio 7.76 and 7.52, respectively). DRB1*04:01 and *04:02 were also predisposing for T1D in Arabs. Very strong evidence supported the protective effects of DRB1*10:01, *13:01, *15:02 and *16:01, with low heterogeneity and no publication bias. The results from the series of meta-analyses performed in this study help to complete the global genetic epidemiological map of T1D by providing statistically robust data from the Arab World.

Family-based association study of HLA class II with type 1 diabetes in Moroccans

BACKGROUND

The T1D is a multifactorial disease; with a strong genetic control. The human leukocyte antigen (HLA) system plays a crucial role in the autoimmune process leading to childhood diabetes. About 440,000 of the childhood population of the world (1.8 billion children under 14 years of age), have type 1 diabetes, and each year an additional 70,000 develop this disorder. The objective of this study was to investigate the distribution of HLA class II in Moroccan families of diabetic children to identify susceptibility alleles of the Moroccan population.

SUBJECTS AND METHODS

We included in this study, Moroccan families who have at least one child with T1D. The age of onset of diabetes was less than 15 years. HLA class II (DRB1* and DQB1*) was carried out by molecular biology techniques (PCR-SSP and PCR-SSO). The FBAT test (family-based association test) was used to highlight the association between T1D and the HLA-DRB1* and -DQB1* polymorphism.

RESULTS

The association of HLA class II (DRB1*, DQB1*) in type 1 diabetes was analyzed in fifty-one Moroccan families, including 90 diabetics. The results revealed that the most susceptible haplotypes are the DRB1*03:01-DQB1*02:01, DRB1*04:05-DQB1*03:02 (Z=3.674, P=0.000239; Z=2.828, P=0.004678, respectively). And the most protective haplotype is the DRB1*15-DQB1*06.

CONCLUSION

This is the first family-based association study searching for an association between HLA class II and T1D in a Moroccan population. Despite the different ethnic groups forming Morocco, Moroccan diabetics share the most susceptible and protective HLA haplotypes with other Caucasians populations, specifically the European and Mediterranean populations.

Association of HLA-DR/DQ polymorphisms with schizophrenia in Tunisian patients

BACKGROUND AND OBJECTIVES

The hypothesis that human leukocyte antigens (HLAs) confer susceptibility to schizophrenic disorders has been tested by studying linkage and association in family samples. Our goal was to evaluate the role of HLA in the risk of developing schizophrenia in a Tunisian population.

DESIGN AND SETTINGS

Blood samples for this case-control study were collected from patients of the Department of Psychiatry at the Military Hospital of Tunisia between July 2012 and May 2013.

METHODS

A total of 140 patients with schizophrenia were recruited for genetic analysis. Controls included 100 persons matched for age, sex, and risk factors. Participants were tested for HLA class II alleles. HLA-DRB1 and HLA-DQB1 alleles were genotyped using polymerase chain reaction sequence-specific primers.

RESULTS

This study indicates that the alleles most responsible for disease susceptibility are DRB1*03 (P < 10-3) and DQB1*02 (P < 10-3) (P denotes probability values). The most protective alleles are DRB1*13 (P=.013) and DQB1*05 (P < 10-3). Further results revealed that DRB1*0301/DQB1*0201(P < 10-3), DRB1*0401/DQB1*0301 (P < 10-3) and DRB1*1101/DQB1*0301 (P < 10-3) are haplotypes most conducive to disease susceptibility.

CONCLUSION

The present findings support an association between schizophrenia and the HLA-DR-DQ locus among a Tunisian population. To our knowledge, this is the first study performed to analyze the association of HLA DRB1/DQB1 alleles on schizophrenia susceptibility in Tunisia.