A. Shtauvere-Brameus

Genetics of Latent Autoimmune Diabetes in Adults

Abstract: Slowly progressive insulin‐dependent diabetes mellitus (IDDM), like classical IDDM, is also associated with genetic markers. HLA‐DR3 but not DR4 is associated with latent autoimmune diabetes in adults (LADA). In GAD65 antibody‐positive Finnish LADA patients, DQB1*0302 is positively associated with the disease. Alleles of the MHC class I chain‐related A (MICA) gene located centromeric to the HLA‐B gene is associated with LADA. Allele 5.1 of MICA was associated with both LADA and adult‐onset Italian IDDM patients when compared to controls. This finding was also observed in Indian and Latvian patients with LADA. These findings suggest that certain genetic markers distinguish LADA better.

BCG vaccination and GAD65 and IA-2 autoantibodies in autoimmune diabetes in southern India.

Abstract: This paper reports a study to determine whether BCG vaccination is associated with an increase or decrease in GAD65 and I‐A2 autoantibodies in cases of IDDM and NIDDM in southern India. It is concluded that BCG vaccination has an immunomodulatory role in these diseases.

MHC Class I Chain‐Related Gene A Alleles Distinguish Malnutrition‐Modulated Diabetes, Insulin‐Dependent Diabetes, and Non‐Insulin‐ Dependent Diabetes Mellitus Patients from Eastern India

Abstract: Insulin‐dependent diabetes mellitus (IDDM) is a polygenic disorder with an autoimmune basis for disease development. In addition to HLA, a second susceptibility locus for IDDM has been identified to lie in the major histocompatibility class III region. MIC‐A is located in the MHC class III region and is expressed by monocytes, keratinocytes, and endothelial cells. Sequence determination of the MIC‐A gene identifies trinucleotide repeat (GCT) microsatellite polymorphism in exon 5. Five alleles with 4, 5, 6, and 9 repetitions of GCT or 5 repetitions of GCT with 1 additional nucleotide insertion (GGCT) are identified. The alleles are A4, A5, A5.1, A6, and A9. The aim of our study was to find the association of MIC‐A alleles with IDDM, malnutrition‐modulated diabetes mellitus (MMDM), and non‐insulin‐dependent diabetes mellitus (NIDDM) patients. IDDM (n= 52), MMDM (n= 41), NIDDM (n= 212), and healthy controls (n= 73) from Cuttack, in eastern India, were studied. Of the 212 NIDDM patients analyzed, 96 of them were found to be positive for either GAD65 or IA‐2 antibodies. Autoantibodies to GAD65 and IA‐2 were measured by radioligand binding assay using 35S‐labeled recombinant human GAD65 and IA‐2 in an in vitro transcription/translation system. Autoantibody‐positive NIDDM patients (n= 96) and adult healthy controls for NIDDM (n= 113) were also compared. These autoantibody‐positive NIDDM patients are considered as slow‐onset IDDM or latent autoimmune diabetes in adults (LADA) patients. The samples were analyzed for MIC‐A by PCR amplification, and fragment sizes were determined in an ABI prism DNA sequencer. The results of the MIC‐A typing are: allele 9 of MIC‐A is positively associated (OR 3.62; P < 0.001), and allele 4 is negatively associated (OR 0.31; P < 0.05) with MMDM patients compared to controls. Allele 5 is positively associated with IDDM (OR 2.64; P < 0.05) when compared to controls. Allele 5.1 is positively associated in the autoantibody‐positive NIDDM patients compared to adult controls. Our findings of a significant increase of allele A9 in MMDM patients compared to healthy controls suggest that MMDM is immunogenetically different from IDDM in eastern India. MIC‐A is important in the pathogenesis of MMDM patients from Cuttack. MIC‐A alleles distinguish acute‐onset IDDM from slow‐onset IDDM, indicating that this molecule may be important for delaying the onset of IDDM with the result that these patients are diagnosed clinically as NIDDM.

Microsatellite Allele 5 of MHC Class I Chain-Related Gene A Increases the Risk for Insulin-Dependent Diabetes Mellitus in Latvians

Abstract: Insulin‐dependent diabetes mellitus (IDDM) is one of the most common chronic diseases. It is an autoimmune, polygenic disease, associated with several genes on different chromosomes. The most important gene is human leukocyte antigen (HLA), also known as major histocompatibility complex (MHC), which is located on chromosome 6p21.3. HLA‐DQ8/DR4 and DQ2/DR3 are positively associated with IDDM and DQ6 is negatively associated with IDDM in most Caucasian populations. The MICA gene is located in the MHC class I region and is expressed by monocytes, keratinocytes, and endothelial cells. Sequence determination of the MICA gene identifies 5 alleles with 4, 5, 6, and 9 repetitions of GCT or 5 repetitions of GCT with 1 additional insertion (GGCT), and the alleles are referred to as A4, A5, A5.1, A6, and A9. Analysis of allele distribution among 93 Latvian IDDM patients and 108 healthy controls showed that allele A5 of MICA is significantly increased in IDDM patients [33/93 (35%)] compared to healthy controls [22/108 (20%)] (OR = 2.15; P= 0.016). In conclusion, we believe that MICA may play an important role in the etiopathogenesis of IDDM.

Newborn screening for high-risk human leukocyte antigen markers associated with insulin-dependent diabetes mellitus: the ABIS study.

Abstract: Type 1 (insulin‐dependent) diabetes mellitus is associated with specific high‐risk HLA DQ and DR haplotypes and islet cell antibodies. IDDM susceptibility in Caucasians is more strongly associated with DQ2/DQ8 (DQA1*0501‐DQB1*0201/DQA1*0301‐DQB1*0302) and DQ6 (B1*0604) than with DRB1*03/DRB1*04, while a single copy of DQ6 (B1*0602) gives sufficient protection against type 1 diabetes. As a part of the ABIS (All Babies in Southeast Sweden) study we have done typing of DQA1, DQB1, and DRB1 by polymerase chain reaction (PCR) amplification of the second exon of the genes, manually dot‐blotting onto nylon membranes synthetic sequence‐specific oligonucleotide (SSO) probes, 3′ end‐labeling with 32P‐dCTP, and hybridization followed by stringency washes and autoradiography using the SSO probe. Among 3756 newborns born in southeast Sweden we have found the high‐risk genotype DQ2/DR3‐DO8/DR4 to be present in 1%, haplotype DQ8/DR4 in 7.8%, and haplotype DQ2/DR3 in 9.6%. DQ2/DR3 or DQ8/DR4 was carried by 16.4% of newborns; the low‐risk DQ6 molecule was carried by newborns as follows: DQ2/DR3‐DQ6/DR15, 1.3%; DQ8/DR4‐DQ6/DR15, 1.3%; and DQ6/DR15, 9.4%. We conclude from our results that the high incidence of IDDM in Sweden is at least in part due to increased prevalence of high‐risk HLA haplotypes compared to protective haplotypes (20% vs. 13%) in the general population.

Prevalence of ICA-12 and other autoantibodies in north Indian patients with early-onset diabetes.

Abstract: This study attempts to assess the prevalence of various autoantibodies in early‐onset diabetics in northern India, with emphasis on antibodies against glutamic acid decarboxylase (GAD65), IA‐2, ICA‐12, 21‐hydroxylase (21‐OH), and tissue transglutaminase (TTG). GAD65 and IA‐2 antibodies were found to be present in approximately 26% of cases of type 1 diabetes. A subset of patients clinically diagnosed to have MMDM appears to have an autoimmune etiology, with more than 20% showing serpositivity for IA‐2 antibodies. Antibodies against ICA‐12 were prevalent in both type 1 diabetes and MMDM. Approximately one of seven patients with type 1 diabetes showed erological evidence of celiac disease.

DR3 Is Associated with Type 1 Diabetes and Blood Group ABO Incompatibility

Abstract: Type 1 diabetes is associated with autoimmunity against pancreatic β cells. ABO incompatibility is associated with ABO immunization during pregnancy. Type 1 diabetes is associated with certain HLA DR and DQ haplotypes. The mechanism by which blood group incompatibility is associated with the risk of type 1 diabetes is not known. We propose that certain HLA alleles contribute to the development of both type 1 diabetes and ABO blood group incompatibility. We studied 57 children with ABO blood group incompatibility, 118 children with type 1 diabetes, and 98 age‐ and sex‐matched unrelated healthy controls from Linköping. Typing of HLA DQA1, DQB1, and DRB1 was done on DNA extracted from peripheral blood, by PCR amplification, manual dot‐blotting onto nylon membranes, synthetic sequence‐specific oligonucleotide (SSO) probe 3′ end‐labeling with 32P‐dCTP, and hybridization followed by stringency washes and autoradiography. We observed that DR3 allele was more frequent in patients with ABO incompatibility when compared to healthy controls (OR = 2.7, Pc < 0.05). Patients with type 1 diabetes had significantly higher frequency of DR3, DQ2, DR4, and DQ8 alleles when compared to healthy controls. No significant difference was observed in frequency of DR3 between ABO blood group incompatibility and type 1 diabetes patients. We conclude that DR3 is associated with both the development of type 1 diabetes and ABO incompatibility.

Microsatellite Allele A5.1 of MHC Class I Chain-Related Gene A Is Associated with Latent Autoimmune Diabetes in Adults in Latvia

Abstract: NIDDM is one of the most common forms of diabetes. The diagnosis is based on WHO classification, which is a clinical classification and misses the autoimmune diabetes in adults. Therefore, among the clinically diagnosed NIDDM cases, there can be a certain number of patients with latent autoimmune diabetes in adults (LADA). The MICA gene is located in the MHC class I region and is expressed by monocytes, keratinocytes, and endothelial cells. Sequence determination of the MICA gene identifies trinucleotide repeat (GCT) microsatellite polymorphism, which identifies 5 alleles with 4, 5, 6, and 9 repetitions of GCT (A4, A5, A6, and A9) or 5 repetitions of GCT with 1 additional G insertion for allele A5.1. From our previous studies, we have shown that microsatellite allele A5 of MICA is associated with IDDM. The aim of this study was to test the hypothesis that certain MICA alleles are associated with LADA among clinically diagnosed NIDDM. Out of 100 clinically diagnosed NIDDM patients, 49 tested positive for GAD65 and IA‐2 antibodies by use of 35S RIA. Samples from these 49 patients and 96 healthy controls were analyzed for MICA by PCR amplification, and fragment sizes were determined in an ABI prism DNA sequencer. Our results show that MICA allele A5.1 is significantly increased in antibody‐positive (GAD65 or IA‐2) NIDDM patients [35/49 (72%)] when compared to healthy controls [22/96 (23%)] (OR = 8.4; P < 0.0001). However, we do not see any association with each of the antibodies separately. From our study, we conclude that (a) MICA allele A5.1 is associated with LADA and (b) MICA may play an important role in the etiopathogenesis of LADA.

Autoantibodies to tissue transglutaminase in patients from eastern India with malnutrition-modulated diabetes mellitus, insulin-dependent diabetes mellitus, and non-insulin-dependent diabetes mellitus.

Abstract: Antibodies to tyrosine phosphatase (IA2‐Ab) and glutamate decarboxylase 65 (GAD65‐Ab) are major markers for IDDM in Caucasians. TTG‐Ab is specific for celiac disease. Celiac disease is caused by ingestion of the protein gliadin, a component of wheat gluten, and usually resolves on its withdrawal. Ten to twenty percent of celiac disease patients also have IDDM. The aim of the study was to estimate the prevalence of TTG‐Ab in MMDM (n= 71), IDDM (n= 74), and NIDDM (n= 216) and 122 controls from Cuttack in eastern India. MMDM patients are typically young at onset with low body mass index, require insulin for glycemic control, have insulin resistance, and do not develop ketosis on withdrawal of insulin. TTG‐Ab was evaluated by radioimmunoassay using in vitro translated recombinant human 35S‐TTG. In controls, TTG‐Ab was present in 3/122 (2%); in MMDM, TTG‐Ab was present in 14/71 (20%); 11/74 (15%) IDDM (P < 0.05 vs. controls) and 23/216 (11%) NIDDM (P < 0.05 vs. controls) were also positive for TTG‐Ab. We conclude that MMDM, IDDM, and NIDDM patients from Cuttack have a significantly high proportion of TTG‐Ab compared to healthy controls. The highest significance is seen with MMDM patients. It is important to note that subclinical celiac disease must be considered in the differential diagnosis of MMDM.

Tumor Necrosis Factor-α Allele 2 Shows an Association with Insulin-Dependent Diabetes Mellitus in Latvians

Abstract: Insulin‐dependent diabetes mellitus (IDDM) is one of the most common chronic diseases. It is an autoimmune disease. Genes contributing the most for development of IDDM are located on chromosome 6p21.3 in the region called the major histocompatibility complex (MHC). HLA‐DQ8/DR4 and DQ2/DR3 have shown positive association with IDDM, while DQ6 has negative association with IDDM in most Caucasian populations. The location of the tumor necrosis factor alpha (TNF‐α) gene in the MHC suggests the role of TNF in the etiology of IDDM as an autoimmune disease. The TNF region contains several polymorphisms that are associated with different levels of TNF‐α production and susceptibility to autoimmune and infectious diseases. Ninety‐two Latvian IDDM patients corresponding to WHO diagnostic criteria and 107 unrelated age‐ and sex‐matched healthy controls were analyzed for the frequency of TNF‐α alleles to test the hypothesis that TNF‐α is associated with IDDM. We found that TNF‐α microsatellite allele 2 is associated with IDDM, 29/92 (32%), versus 14/107 (13%) in healthy controls. The test of the strongest association of the MICA A5 allele and TNF‐α allele 2 with IDDM showed that both are independently associated with the disease.