Prevalence of human leukocyte antigen DQA1 and DQB1 alleles in Kuwaiti Arab children with type 1 diabetes mellitus

Linkage analysis using whole exome sequencing data implicates SLC17A1, SLC17A3, TATDN2 and TMEM131L in type 1 diabetes in Kuwaiti families

Type 1 diabetes (T1D) is characterized by the progressive destruction of pancreatic β-cells, leading to insulin deficiency and lifelong dependency on exogenous insulin. Higher estimates of heritability rates in monozygotic twins, followed by dizygotic twins and sib-pairs, indicate the role of genetics in the pathogenesis of T1D. The incidence and prevalence of T1D are alarmingly high in Kuwait. Consanguineous marriages account for 50-70% of all marriages in Kuwait, leading to an excessive burden of recessive allele enrichment and clustering of familial disorders. Thus, genetic studies from this Arab region are expected to lead to the identification of novel gene loci for T1D. In this study, we performed linkage analyses to identify the recurrent genetic variants segregating in high-risk Kuwaiti families with T1D. We studied 18 unrelated Kuwaiti native T1D families using whole exome sequencing data from 86 individuals, of whom 37 were diagnosed with T1D. The study identified three potential loci with a LOD score of ≥ 3, spanning across four candidate genes, namely SLC17A1 (rs1165196:pT269I), SLC17A3 (rs942379: p.S370S), TATDN2 (rs394558:p.V256I), and TMEM131L (rs6848033:p.R190R). Upon examination of missense variants from these genes in the familial T1D dataset, we observed a significantly increased enrichment of the genotype homozygous for the minor allele at SLC17A3 rs56027330_p.G279R accounting for 16.2% in affected children from 6 unrelated Kuwaiti T1D families compared to 1000 genomes Phase 3 data (0.9%). Data from the NephQTL database revealed that the rs1165196, rs942379, rs394558, and rs56027330 SNPs exhibited genotype-based differential expression in either glomerular or tubular tissues. Data from the GTEx database revealed rs942379 and rs394558 as QTL variants altering the expression of TRIM38 and IRAK2 respectively. Global genome-wide association studies indicated that SLC17A1 rs1165196 and other variants from SLC17A3 are associated with uric acid concentrations and gout. Further evidence from the T1D Knowledge portal supported the role of shortlisted variants in T1D pathogenesis and urate metabolism. Our study suggests the involvement of SLC17A1, SLC17A3, TATDN2, and TMEM131L genes in familial T1D in Kuwait. An enrichment selection of genotype homozygous for the minor allele is observed at SLC17A3 rs56027330_p.G279R variant in affected members of Kuwaiti T1D families. Future studies may focus on replicating the findings in a larger T1D cohort and delineate the mechanistic details of the impact of these novel candidate genes on the pathophysiology of T1D.

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.

HLA pharmacogenetic markers of drug hypersensitivity from the perspective of the populations of the Greater Middle East

Specific HLA associations with drug hypersensitivity may vary between geographic regions and ethnic groups. There are little to no data related to HLA-drug hypersensitivity on populations who reside in the Greater Middle East (GME), a vast region spanning from Morocco in the west to Pakistan in the east. In this review, the authors intended to summarize the significant HLA alleles associated with hypersensitive drug reactions induced by different drugs, as have been found in different populations, and to summarize the prevalence of these alleles in the specific and diverse populations of the GME. For example, HLA-B*57:01 allele prevalence, associated with abacavir-induced hypersensitivity, ranges from 1% to 3%, and HLA-DPB1*03:01 prevalence, associated with aspirin-induced asthma, ranges from 10% to 14% in the GME population. Studying pharmacogenomic associations in the ethnic groups of the GME may allow the discovery of new associations, confirm ones found with a low evidence rate and enable cost-effectiveness analysis of allele screening before drug use.

Clinical features, epidemiology, autoantibody status, HLA haplotypes and genetic mechanisms of type 1 diabetes mellitus among children in Qatar

To describe the clinical features, epidemiology, autoantibody status, HLA haplotypes and genetic mechanisms of type 1 diabetes mellitus (T1DM). Patients (0-18 years) with diabetes were recruited. Clinical data was collected, autoantibodies and c-peptide were measured. Whole Genome Sequencing was performed. Genomic data analysis was compared with the known genes linked with T1DM and HLA alleles were studied. 1096 patients had one or more antibody positivity. The incidence of T1DM in 2020 was 38.05 per 100,000 children and prevalence was 249.73. GADA was the most common autoantibody followed by IAA. Variants in GSTCD, SKAP2, SLC9B1, BANK1 were most prevalent. An association of HLA haplotypes DQA1*03:01:01G (OR = 2.46, p value = 0.011) and DQB1*03:02:01G (OR = 2.43, p value = 0.022) was identified. The incidence of T1DM in Qatar is the fourth highest in the world, IA2 autoantibody was the most specific with some patients only having ZnT8 or IA2 autoantibodies thus underlining the necessity of profiling all 4 autoantibodies. The genes associated with T1DM in the Arab population were different from those that are common in the Caucasian population. HLA-DQ was enriched in the Qatari patients suggesting that it can be considered a major risk factor at an early age.

Association of HLA-DRB1 and -DQ Alleles and Haplotypes with Type 1 Diabetes in Jordanians

BACKGROUND

The Human Leukocyte Antigen (HLA) class II genes, particularly the HLADR and -DQ loci, have been shown to play a crucial role in Type 1 Diabetes (T1D) development.

OBJECTIVE

This study is the first to examine the contribution of the HLA-DR/DQ alleles and haplotypes to T1D susceptibility in Jordanians.

METHODS

Polymerase chain reaction sequence-specific primers (PCR-SSP) were used to genotype 41 Jordanian healthy controls and 50 insulin-dependent diabetes mellitus (IDDM) patients.

RESULTS

The following alleles were found to be significant high risk alleles in T1D Jordanian patients: DRB1*04 (OR=3.95, p<0.001), DRB1*0301(OR=5.27, p<0.001), DQA1*0301 (OR=5.67, p<0.001), DQA1*0501(OR=3.18, p=0.002), DQB1*0201(OR=2.18, p=0.03), DQB1*0302 (OR=5.67, p<0.001). However, Jordanians harboring the DRB1*0701 (OR=0.37, p=0.01), DRB1*1101 (OR=0.2, p=0.01), DQA1*0505 (OR=0.31, p=0.02), DQA1*0103 (OR=0.33, p=0.04), DQA1*0201 (OR=0.45, p=0.04), DQB1*0301 (OR=0.23, p=0.001), DQB1*0501 (OR=0.18, p=0.009) alleles had a significantly lower risk of developing T1D.

CONCLUSION

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. Our findings show that specific HLA class II alleles and haplotypes are significantly associated with susceptibility to T1D in Jordanians.

Human Leukocyte Antigen (HLA) and Islet Autoantibodies Are Tools to Characterize Type 1 Diabetes in Arab Countries: Emphasis on Kuwait

The incidence rate of type 1 diabetes in Kuwait had been increasing exponentially and has doubled in children ≤ 14 years old within almost two decades. Therefore, there is a dire need for a careful systematic familial cohort study. Several immunogenetic factors affect the pathogenesis of the disease. The human leukocyte antigen (HLA) accounts for the major genetic susceptibility to the disease. The triggering agents initiate disease onset by type 1 destruction of pancreatic β-cells. Both HLA and anti-islet antibodies can be used to characterize, predict susceptibility to the disease, innovate, or delay the β-cell destruction. Evidence from prospective longitudinal studies suggested that the underlying disease process represents a continuum that begins before the symptoms are clinically evident. Autoimmunity of the functional pancreatic β-cells results in symptomatic type 1 diabetes and lifelong insulin dependence. The autoantibodies against glutamic acid decarboxylase (GADA), insulinoma antigen-2 (IA-2A), insulin (IAA), and zinc transporter-8 (ZnT-8A) comprise the most reliable biomarkers for type 1 diabetes in both children and adults. Although Kuwait is the second among the top 10 countries with a high incidence rate of type 1 diabetes, there have been no proper diagnostic and prediction tools as per the World Health Organization. The Kuwaiti Type 1 Diabetes Study (KADS) was initiated to understand the disease pathogenesis as well as the HLA and anti-islet autoantibody profile of type 1 diabetes in Kuwait. Understanding the disease sequela in a homogenous gene pool and highly consanguineous population of Kuwaitis could help solve the challenges and pathogenesis, as well as hasten the prevention, of type 1 diabetes.

Association of protein tyrosine phosphatase non-receptor type 22 gene functional variant C1858T, HLA-DQ/DR genotypes and autoantibodies with susceptibility to type-1 diabetes mellitus in Kuwaiti Arabs

The incidence of type-1 Diabetes Mellitus (T1DM) has increased steadily in Kuwait during recent years and it is now considered amongst the high-incidence countries. An interaction between susceptibility genes, immune system mediators and environmental factors predispose susceptible individuals to T1DM. We have determined the prevalence of protein tyrosine phosphatase non-receptor type 22 (PTPN22) gene functional variant (C1858T; R620W, rs2476601), HLA-DQ and DR alleles and three autoantibodies in Kuwaiti children with T1DM to evaluate their impact on genetic predisposition of the disease. This study included 253 Kuwaiti children with T1DM and 214 ethnically matched controls. The genotypes of PTPN22 gene functional variant C1858T (R620W; rs2476601) were detected by PCR-RFLP method and confirmed by DNA sequencing. HLA-DQ and DR alleles were determined by sequence-specific PCR. Three autoantibodies were detected in the T1DM patients using radio-immunoassays. A significant association was detected between the variant genotype of the PTPN22 gene (C1858T, rs2476601) and T1DM in Kuwaiti Arabs. HLA-DQ2 and DQ8 alleles showed a strong association with T1DM. In T1DM patients which carried the variant TT-genotype of the PTPN22 gene, 93% had at least one DQ2 allele and 60% carried either a DQ2 or a DQ8 allele. Amongst the DR alleles, the DR3-DRB5, DR3-3, DR3-4 and DR4-4 showed a strong association with T1DM. Majority of T1DM patients who carried homozygous variant (TT) genotype of the PTPN22 gene had either DR3-DRB5 or DRB3-DRB4 genotypes. In T1DM patients who co-inherited the high risk HLA DQ, DR alleles with the variant genotype of PTPN22 gene, the majority were positive for three autoantibodies. Our data demonstrate that the variant T-allele of the PTPN22 gene along with HLA-DQ2 and DQ8 alleles constitute significant determinants of genetic predisposition of T1DM in Kuwaiti children.

The genetic heterogeneity of Arab populations as inferred from HLA genes

This is the first genetic anthropology study on Arabs in MENA (Middle East and North Africa) region. The present meta-analysis included 100 populations from 36 Arab and non-Arab communities, comprising 16,006 individuals, and evaluates the genetic profile of Arabs using HLA class I (A, B) and class II (DRB1, DQB1) genes. A total of 56 Arab populations comprising 10,283 individuals were selected from several databases, and were compared with 44 Mediterranean, Asian, and sub-Saharan populations. The most frequent alleles in Arabs are A*01, A*02, B*35, B*51, DRB1*03:01, DRB1*07:01, DQB1*02:01, and DQB1*03:01, while DRB1*03:01-DQB1*02:01 and DRB1*07:01-DQB1*02:02 are the most frequent class II haplotypes. Dendrograms, correspondence analyses, genetic distances, and haplotype analysis indicate that Arabs could be stratified into four groups. The first consists of North Africans (Algerians, Tunisians, Moroccans, and Libyans), and the first Arabian Peninsula cluster (Saudis, Kuwaitis, and Yemenis), who appear to be related to Western Mediterraneans, including Iberians; this might be explained for a massive migration into these areas when Sahara underwent a relatively rapid desiccation, starting about 10,000 years BC. The second includes Levantine Arabs (Palestinians, Jordanians, Lebanese, and Syrians), along with Iraqi and Egyptians, who are related to Eastern Mediterraneans. The third comprises Sudanese and Comorians, who tend to cluster with Sub-Saharans. The fourth comprises the second Arabian Peninsula cluster, made up of Omanis, Emiratis, and Bahrainis. It is noteworthy that the two large minorities (Berbers and Kurds) are indigenous (autochthonous), and are not genetically different from "host" and neighboring populations. In conclusion, this study confirmed high genetic heterogeneity among present-day Arabs, and especially those of the Arabian Peninsula.

HLA-DQB1 Subtypes Predict Diabetic Retinopathy in Patients with Type I Diabetes Mellitus

Purpose

To investigate if diabetic patients without diabetic retinopathy despite long disease duration have different human leukocyte antigen (HLA) status vs those with an early onset of retinopathy.

Methods

Retrospective, nonrandomized, masked comparative study. Type 1 diabetic patients with a disease onset before age 30 were recruited to the study. The study population consisted of two groups of diabetic patients: those with normal retinopathy course (retinopathy developed during the first 20 years of diabetes onset) (23 patients) and those with postponed retinopathy (no obvious retinopathy in spite of passing 20 years of diabetes) (19 patients). These groups were matched with regard to level of glycemic control, blood pressure, and lipid profile. A group of 23 healthy patients served as controls. HLA-DQB1 typing of blood samples was done using a polymerase chain reaction with sequence-specific primer (PCR-SSP) method.

Results

HLA-DQB1*0201/HLA-DQB1*0501 and HLA-DQB1*0201/HLA-DQB1*0504 haplotypes were more common among type 1 diabetic patients with normal retinopathy course than those with postponed retinopathy (26.1% vs 0.0%; p=0.019). HLA-DQB1*0301 and HLA-DQB1*0304 were less common among those diabetic patients with normal retinopathy course than those with a postponed retinopathy (63.2% vs 34.8%; p=0.067).

Conclusions

Some haplotypes seem to predispose diabetic patients to diabetic retinopathy. HLA typing may be beneficial for predicting the prognosis of diabetic retinopathy in younger diabetic patients.

Incidence of type 1 diabetes has doubled in Kuwaiti children 0-14 years over the last 20 years

AIMS

This study had 2 aims: to report data on the incidence of childhood-onset type 1 diabetes in Kuwaiti children aged 0-14 years during 2011 to 2013 and to compare the recent data with those collected during 1992 to 1997.

METHODS

All newly diagnosed patients were registered through the Childhood-Onset Diabetes eRegistry (CODeR) in 2011-2013, based on the DiaMond protocol used in 1992-1997.

RESULTS

A total of 515 Kuwaiti children (247 boys and 268 girls) aged 0-14 years newly diagnosed with type 1 diabetes were registered from 1 January 2011 to 31 December 2013. Data ascertainment were 96.7%. The mean age ± SD at diagnosis was 8.7 ± 3.4 years in boys and 7.9 ± 3.1 years in girls. The crude incidence rate (95% CI) was 40.9 (37.4-44.6) and the age standardized rate 41.7 (95% 38.1-45.4) per 100,000 per year, 39.3 (34.6-44.4) among boys and 44.1 (39.0-49.7) among girls. A statistically significant increasing trend in incidence was observed as the overall crude incidence rose from 17.7 in 1992-1994 to 40.9 per 100,000 per year in 2011-2013. The Poisson regression model depicting the trend in incidence revealed that, the incidence rates adjusted for age and sex in 2011 to 2013 was 2.3 (95% CI 1.9-2.7) times higher than 1992-1997.

CONCLUSIONS

The incidence of type 1 diabetes in Kuwaiti children 0-14 years has doubled in the last 2 decades. The reasons for this increase requires further investigation.

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.

Prevalence of thyroid autoantibodies in children, adolescents and young adults with type 1 diabetes in Kuwait

OBJECTIVE

To investigate the prevalence of thyroid autoimmunity among children and adolescents with type 1 diabetes in Kuwait.

SUBJECTS AND METHODS

In a mixed cross-sectional and longitudinal study, anti-thyroid peroxidase (anti-TPO) and anti-thyroglobulin (anti-TG) were measured in 232 subjects (118 males and 114 females) with type 1 diabetes.

RESULTS

The mean age of the total study population was 10.9 ± 3.6 years (range 1-21), and the median diabetes duration was 3.9 years (range 0-16). At the initial screening, 57 out of 232 (24.6%) patients had positive antibodies, and of the remaining 175 patients, who were antibody negative,131 (74.3%) were followed up for 4-9 years. 23 out of these 131 (17.7%) patients became antibody positive, with a cumulative prevalence of elevated antibodies of 34.5%. Anti-TPO was present in 34 (14.7%), anti-TG in 23 (9.9%) and both antibodies in 23 (9.9%) patients. Thyroid antibodies presented early within the first 5 years of the onset of diabetes (63.2 vs. 36.8%, p < 0.05). The prevalence of elevated thyroid antibodies increased after the onset of puberty in both females and males (p < 0.0001). A total of 58.7% of the patients with positive antibodies were females compared to 41% males (p < 0.0001). The basal thyroid-stimulating hormone was higher in subjects with positive antibodies (5.1 ± 10.7 mIU/l) compared to those who were antibody negative (1.79 ± 0.87 mIU/l, p < 0.001). Furthermore, 30 out of 232 (12.9%) patients developed thyroid dysfunction.

CONCLUSION

In this study, a high prevalence of thyroid autoimmune antibodies was found in patients either at the onset of type 1 diabetes or within the 4-9 years of follow-up.

HLA-DQB1* alleles and genetic susceptibility to type 1 diabetes mellitus

AIM: To determine human leukocyte antigen (HLA)-DQB1 allele association with susceptibility to type 1 diabetes (T1D) and to clinical and laboratory findings.

METHODS: This study was conducted on 85 unrelated Egyptian children with T1D recruited consecutively from the Pediatric Diabetes Endocrinology outpatients Clinic; Mansoura University Children’s Hospital, Egypt. Patient mean follow up period was 2.5 years. Patients were subdivided according to level of HbA1c (optimal/suboptimal control < 8.5% and poor control ≥ 8.5%). The control group consisted of 113 unrelated age- and sex-matched healthy subjects without T1D or other autoimmune diseases. Genomic DNA extraction was done for all subjects using a DNA isolation kit. HLA-Class II-DQB1 allele typing was carried out with a polymerase chain reaction-sequence-specific oligonucleotide probe using a INNO-LiPA HLA-DQB1 update kit.

RESULTS: Significant differences were detected between Egyptian patients with T1D and control groups in the frequencies of DQB1*02 [44.4% vs 18.6%, corrected P value (Pc) < 0.001] and DQB1*03 (41.2% vs 24.4%, Pc < 0.001). Significant differences were also observed between control groups and T1D patients in the frequencies of DQB1*05 (14.6% vs 7.2%, P = 0.029) and DQB1*06 (34.1% vs 7.2%, P < 0.001). However, after correction for multiple comparisons, the significance was retained for HLA-DQB1*06 (Pc < 0.001) but lost for HLA-DQB1*05. HLA-DQB1*0201, *0202, *030201 were positively associated with T1D (Pc = 0.014, Pc < 0.001, and Pc < 0.001 respectively), while HLA-DQB1*060101 was negatively associated (Pc < 0.001) with the condition. Although the HLA-DQB1 alleles 030101 and 050101 were significantly higher in controls (P = 0.016, P = 0.025 respectively), both of them lost statistical significance after correction of P value. The frequency of the HLA-DQB1 genotypes 02/02, 02/03, and 03/03 was higher in T1D patients, and the frequency of the genotypes 03/06, 05/06, and 06/06 was higher in controls, these differences being statistically significant before correction. After correction, the genotypes 02/02, 02/03 in T1D, and the genotypes 03/06, 06/06 in controls were still significant (Pc = 0.01, Pc < 0.001, Pc < 0.001, and Pc = 0.04, respectively). Non-significant associations were found between the frequency HLA-DQB1 alleles and genotypes in T1D in relation to the grade of diabetic control, Microalbuminuria, age, gender, age of presentation, weight, height, frequency of diabetic ketoacidosis (P = 0.42), serum cholesterol, and fasting and post-prandial level of C-peptide (P = 0.83, P = 0.9, respectively).

CONCLUSION: The Current work suggests that HLA-DQB1 alleles *030201, *0202, *0201, and genotypes 02/03, 02/02 may be susceptibility risk factors for development of T1D in Egyptian children, while the HLA-DQB1*060101 allele, and 03/06, 06/06 genotypes may be protective factors. HLA-DQB1 alleles and genotypes do not contribute to microalbuminuria or grade of diabetic control.

Genetic and diabetic auto-antibody markers in Saudi children with type 1 diabetes

Human leukocyte antigen DRB1 and DQB1 contribute to the genetic susceptibility of type 1 diabetes (T1DM), and they are involved in the induction of the autoimmune destruction of pancreatic beta cells precipitating the disease. The objective of this study was to examine diabetic auto-antibodies (ICA-512, GAD65) and the HLA-DR/DQ genotype among T1DM Saudi children in a cross-sectional study conducted at King Khalid University and National Guard Hospitals, Riyadh. Subjects included in this study were 103 Saudi patients and 180 healthy controls. In all, 41% of patients were positive for ICA512 73.3% positive for GAD65, and 27.3% had both antibodies. The risk alleles were DRB1*0301 (odds ratio [OR] = 11.1); DRB1*0405 (OR = 6.02); DRB1*0401 (OR = 5.8); DQB1*0201 (OR, 17.69) and DQB1*0302 (OR = 3.77). In addition, the DRB1*03/04-DQB1*02/0302 (OR = 123.4) is positively associated with T1DM. However, DRB1*0403 (OR = 0.27), DRB1*1101 (OR = 0.049), DRB1*1307 (OR = 0.28), DRB1*1501 (OR = 0.12), DQB1*0301 (OR = 0.03), DQB1*0401 (OR = 0.04), and DQB1*0602 (OR = 0.16) were protective. Among GAD-positive patients, 81% were DRB1*0301, 68.75% were DQB1*0201, 62.5% were DRB1*0405, 43.75% were DQB1*0302, and 43.7% were DRB1*03/04. Among ICA512-positive patients, all were DRB1*0301, 66.6% were DQB1*0201, 55% were DRB1*0405, 33.3% were DQB1*0302, and 55% were DRB1*03/04. In conclusion, these results show a strong association of HLA-DQB1*0201/0302 and DRB1*03/04 with T1DM. Thus, combining genetic markers with autoantibody is useful in a screening program for early detection of T1DM among Saudi children.

Genetic determinants of type 1 diabetes across populations

T1D results from autoimmune-mediated destruction of the pancreatic beta cells, a process that is conditioned by multiple genes and environmental factors. The main genetic determinants map to the major histocompatibility complex (MHC), and in particular DR and DQ, although, genes outside the MHC contribute, including the insulin gene, PTPN22, and CTLA-4. There are remarkable differences in genetic susceptibility to T1D between populations. We believe this variation reflects differing frequencies of diabetes causative and protective alleles and haplotypes, and thus remains a major genetic influence linked to the MHC region not accounted for by DR and DQ alleles. In this article, we discuss global variations in genetic susceptibility to T1D in view of current genetic understanding.

Prevalence of type 1 diabetes among 6- to 18-year-old Kuwaiti children

OBJECTIVES

To determine the prevalence of type 1 diabetes among 6- to 18-year-old Kuwaiti children according to gender, age, and region.

SUBJECTS AND METHODS

Children with type 1 diabetes aged 6-18 years were identified at 182 schools (50 primary, 63 intermediate, and 69 secondary) in Kuwait during the study period October 2000 to September 2002. Schools were randomly selected using the 2000/01 educational districts' registers as sampling frame proportional to the number of schools in each district. Prevalence rates were adjusted to the 2002 Kuwaiti population. Diagnosis of type 1 diabetes was based on the World Health Organization, and the American Diabetes Association criteria.

RESULTS

Prevalence of type 1 diabetes was 269.9 per 100,000 (95% confidence interval, CI 241.6-298.3). There was no significant difference in prevalence between male (247.6, 95% CI 205.2-290.0) and female (285.5, 95% CI 247.5-323.5). Type 1 diabetes was more prevalent in the age group 10-13 years (347.3), and lowest in the age group 6-9 years (182.6) per 100,000; the difference was significant at p < 0.001. The overall age-adjusted prevalence rate was 252.9 (95% CI 234.6-271.2), 229.1 (95% CI 204.6-253.6) in male and 277.4 (95% CI 250.0-304.7) in female children in the 2002 Kuwaiti population. The mean age at onset was 9.2, and 8.1 years in male and female children, respectively (p = 0.018). There was no significant difference in prevalence between regions.

CONCLUSION

Type 1 diabetes is a common chronic disease in Kuwaiti children.

The rare HLA-DQA1*03-DQB1*02 haplotype confers susceptibility to type 1 diabetes in whites and is preferentially associated with early clinical disease onset in male subjects

The heterozygous combination of DQA1*03-DQB1*0302 (DQ8) and DQA1*05-DQB1*0201 (DQ2) confers the highest known HLA-DQ-linked risk for type 1 diabetes, suggesting a role for transcomplementation. The trans-heterodimer encoded by DQA1*03 and DQB1*02 is also rarely observed in cis in whites. Islet antibody-positive diabetic patients (P; n = 2,238) and control subjects (C; n = 2,223) of white descent were genotyped by a HLA-DQA1-DQB1 dot-blot method. The presence of the DQA1*03-DQB1*02 haplotype was observed in 22 patients (1%) versus 6 controls (0.3%) (odds ratio [OR] = 3.7, p = 0.005). It was more prevalent in whites of Northern African descent, but both in European (n = 3,813) and in Northern African whites (n = 648), the DQA1*03-DQB1*02 haplotype tended to be associated with diabetes (respectively, P 0.3% vs. C 0.03%, OR = 12.2, p = 0.005; and P 2.1% vs. C 0.6%, OR = 3.8, p = 0.03). DRB1 typing revealed that DQA1*03-DQB1*02 is usually associated with the DRB1*0405 risk allele in European patients and with DRB1*0405, DRB1*07 and DRB1*09 in Northern African whites. Like in DQ2/DQ8-positive patients, the presence of DQA1*03-DQB1*02 is preferentially associated with younger age at clinical onset than in other genotypes, but unlike in subjects carrying DQ2/DQ8, earlier clinical manifestation was mostly restricted to male subjects, often carrying DR3 and/or DQB1*02 on the other chromosome. These results are compatible with an effect of cis-encoded heterodimers or with previously suggested interactions of X-linked genetic factors with (DR3-)DQB1*02 haplotypes.

The prevalence of human leukocyte antigen (HLA) DR/DQ/DP alleles in Kuwaiti children with oligoarticular juvenile idiopathic arthritis

We have determined the prevalence of human leukocyte antigen (HLA)-DR, DQ and DP alleles in Kuwaiti children with oligoarticular juvenile idiopathic arthritis (OA-JIA) and healthy controls using the PCR-SSP (sequence specific primers) method. The analysis took into account the presence of antinuclear antibodies and chronic anterior uveitis. DRB1*03 (RR 2.20, P<0.001), DRB1*08 (RR 5.280, P<0.026), DQA1*0501 (RR 1.930, P<0.001), DQB1*0304 (RR 7.920, P<0.002), DQB1*0501 (RR 3.080, P<0.007) and DPB1*0101 (RR 8.8, P<0.001) were the main HLA alleles associated with OA-JIA in Kuwaiti Arabs in this study. DRB1*03 was detected in 71% of children with positive ANA, and in 50% of children with anterior uveitis. DQA1 alleles *0501, *0103 and *0105 (P<0.001; 0.029 and 0.024 respectively) were found to be associated with OA-JIA. In contrast, DQA1*0301 and DQA1*0302 alleles appear to be protective in Kuwaiti children (RR 0.153, P<0.001 and RR 0.278, P<0.016 respectively). The DQB1 alleles *0304 and *0501 were associated with OA-JIA (P<0.002 and P<0.007 respectively). In the case of DPB1, only one allele (*0101) was associated with OA-JIA (P<0.001). Most Kuwaiti Arab patients with OA-JIA who carried a DQ or DP susceptibility allele also had an accompanying DRB1*03 or *8 allele.

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.

Human leukocyte antigen-DQB1 alleles are not associated with schizophrenia in Kuwaiti Arabs

Schizophrenia is among the most severe and debilitating of psychiatric disorders and has a complex mode of inheritance. A susceptibility locus has been identified on chromosome 6 and some association studies involving human leukocyte antigen (HLA) genes have reported diverse results. The objective of the present study was to determine if there is an association between HLA-DQB1 alleles and schizophrenia in Kuwaiti Arabs. The frequency of HLA-DQB1 alleles was determined in a cohort of 195 Kuwaiti Arabs consisting of 81 schizophrenia patients and 114 ethnically matched healthy controls, using a polymerase chain reaction-sequence specific primers method. A total of nine DQB1 alleles were identified in this Kuwaiti cohort. The most prevalent DQB1 alleles in Kuwaiti schizophrenia patients were *0601 (28%), *0201 (23%) and *0501 (16%), respectively. However, no significant difference in the allele frequency was detected between schizophrenia patients and the controls. The DQB1*0602 allele, which has been negatively associated in African-Americans in previous reports, was not detected in the present Kuwaiti schizophrenia patients or controls.

Association of serum sialic acid with cardiovascular metabolic risk factors in Kuwaiti children and adolescents with type 1 diabetes

The aim of the present study was to investigate the relation of serum total sialic acid (TSA) concentrations with cardiovascular metabolic risk factors in Kuwaiti children and adolescents with uncomplicated type 1 diabetes. This case-control study included 150 (57 males and 93 females) type 1 diabetic children aged 6 to 18 years matched by age and sex to 150 nondiabetic children as controls. Measured variables included weight, height, systolic, diastolic blood pressure, and biochemical variables: blood glucose, glycated hemoglobin (HbA(1C)), triglycerides (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL), apolipoproteins (apo) A1 and B, and urine microalbumin. There was no significant difference between mean serum TSA of the type 1 diabetic children (671.0 mg/L) and their controls (663.7 mg/L). In diabetic children, mean serum TSA was significantly higher in females (699.1 mg/L) than in males (625.2 mg/L) (P =.003). Significant correlations were found between serum TSA and the cardiovascular risk factors TC (P =.002), TG (P <.001), and apo B (P =.008). TSA mean level was significantly higher in diabetic children with poor glycemic control (HbA(1C) > 9.0%; P =.015), raised TC (P =.013), raised TG (P =.014), and in children with family history of cardiovascular disease (CVD; P =.02). In conclusion, the study suggests that serum TSA levels were not elevated in young type 1 diabetic children as compared with controls. The study also confirmed significant correlation of TSA concentrations with CVD risk factors TC, TG, and apo B, and as such serum TSA may be considered as a marker for CVD risk, especially in diabetic patients. A long-term prospective study is recommended to ascertain the longitudinal relationship of serum TSA with the adverse metabolic changes in type 1 diabetic children as complications prevail.

Further evidence for the rising incidence of childhood Type 1 diabetes in Kuwait

AIMS

To provide age-gender standardized incidence rate, temporal trend and seasonal variation of Type 1 diabetes in Kuwaiti children aged < or = 14 years.

METHODS

Data were prospectively collected over a period of 6 years (1992-1997) according to the DiaMond Project protocol using the capture-recapture method of ascertainment.

RESULTS

Data ascertainment varied between 90% and 96%. The incidence rate of Type 1 diabetes was 20.1 per 100,000 children 0-14 years (95% confidence interval (CI) 18.0-22.1); age-standardized incidence rate 20.9 (95% CI 18.8-23.0). The incidence rate among boys, 21.1 per 100,000 (95% CI 18.1-24.1) was slightly higher than that among girls, 19.0 per 100,000 (95% CI 16.1-21.8). The age-standardized incidence rate was 21.9 (95% CI 18.9-24.8) in boys, and 19.9 (95 CI 17.1-22.8) in girls. Incidence rates increased with age in both sexes (boys chi(2) for linear trend = 13.5, P < 0.001; and for girls chi(2) = 27.8, P < 0.0001). There was a significant trend towards increase in overall incidence during the 6-year period (chi(2) = 6.210, P = 0.013), and in age group 5-9 (chi(2) = 10.8, P = 0.001). Seasonality was demonstrated overall, in boys and girls (P < 0.001).

CONCLUSION

The incidence of Type 1 diabetes in Kuwait is high compared with the neighbouring Arab countries, and it appears to be increasing as in many European populations.

Reshaping the shared epitope hypothesis: HLA-associated risk for rheumatoid arthritis is encoded by amino acid substitutions at positions 67-74 of the HLA-DRB1 molecule

OBJECTIVE

To further analyze the association of HLA-DRB1 alleles with disease susceptibility in recent-onset rheumatoid arthritis (RA).

METHODS

One hundred sixty-seven Caucasian RA patients and 166 healthy controls were typed for HLA-DRB1.

RESULTS

The association of susceptibility to RA with the group of alleles encoding the shared epitope susceptibility sequences (SESSs) was confirmed in recent-onset RA. Among non-SESS alleles, DRB1*07, *1201, *1301, and *1501 showed significant protective effects. Even after correction for the influence of SESS alleles, significant independent protective effects of DRB1 alleles were observed. Protective alleles shared a third hypervariable region motif. Independent homozygosity effects were observed both for susceptibility and for protective alleles.

CONCLUSION

Nonsusceptibility alleles differ significantly with regard to RA risk. Protective alleles show clear homology at positions 67-74, often encoding isoleucine at position 67 or aspartic acid at position 70. Susceptibility and protective alleles both show homozygosity effects. Based on these results and on data reported in the literature, in order to incorporate the finding of differential risks among nonsusceptibility alleles, we propose to reshape the shared epitope hypothesis as follows: HLA-associated risk for RA is encoded by amino acid substitutions at positions 67-74 of the HLA-DRB1 molecule.

Prevalence of human leukocyte antigen (HLA) DRB1 alleles in Kuwaiti children with juvenile rheumatoid arthritis

The prevalence of human leukocyte antigen (HLA) DR alleles has been determined in 69 Kuwaiti Arab children with juvenile rheumatoid arthritis (JRA) and compared to that in 212 ethnically matched normal healthy controls using a PCR-sequence specific primers (PCR-SSP) method. A very high incidence of DR3 was detected in JRA patients compared to the controls (P < 0.0001, RR = 2.235). The high incidence of HLA-DR3 in JRA patients was accounted for mainly by an excess of DRB1*0307 (P < 0.05, RR = 3.072) and DRB1*0308 (P < 0.009, RR = 2.663) compared to the controls. Moreover, DR3 was more prevalent when patients with ANA-positive JRA were analysed separately; 73% compared to 58% for the whole JRA patient group. The frequency of DR1 was also higher in the JRA group compared to controls (P = 0.019, RR = 3.585). Although the incidence of some alleles was higher in the control group (DR13 and DR7), none reached a statistically significant level. All the patients with iridocyclitis had either a DR1 or DR3 allele, except for one child. The frequency of DRB1*03 was found to be much higher in the polyarticular subtype of Kuwaiti JRA cases compared to the oligoarticular subgroup and the controls. Also, a non-significant increase in the frequency of the DRB1*04, *11 and *15 alleles was detected in the polyarticular subtype of the Kuwaiti JRA cases compared to the controls.