The review is aimed to explore the clinical and pathogenic spectrum of autoimmune diabetes including Type 1 diabetes and latent autoimmune diabetes in adults (LADA). Genetic susceptibility modifies age at onset in autoimmune diabetes. The most important genetic susceptibility to Type 1 diabetes and LADA is in the HLA region. Because of the age-related genetic factors, LADA can not be distinguished from classic Type 1 diabetes by genetics. Non-genetic factors contribute much to Type 1 diabetes, but little is known in LADA. Diabetes-associated immune process can occur in early childhood and can be predictive of an ongoing beta cell destruction. The management and prevention of LADA need to be investigated in order to define the best therapeutic strategy.
Diabetes Mellitus, Type 1 ; etiology ; genetics ; immunology ; therapy ; Humans

Type 1 diabetes (T1D) is an autoimmune disease that resulted from the severe destruction of the insulin-producing β cells in the pancreases of individuals with a genetic predisposition. Genome-wide studies have identified HLA and other risk genes associated with T1D susceptibility in humans. However, evidence obtained from the incomplete concordance of diabetes incidence among monozygotic twins suggests that environmental factors also play critical roles in T1D pathogenesis. Epigenetics is a rapidly growing field that serves as a bridge to link T1D risk genes and environmental exposures, thereby modulating the expression of critical genes relevant to T1D development beyond the changes of DNA sequences. Indeed, there is compelling evidence that epigenetic changes induced by environmental insults are implicated in T1D pathogenesis. Herein, we sought to summarize the recent progress in terms of epigenetic mechanisms in T1D initiation and progression, and discuss their potential as biomarkers and therapeutic targets in the T1D setting.
Diabetes Mellitus, Type 1/genetics* ; Epigenesis, Genetic/genetics* ; Genetic Predisposition to Disease/genetics* ; Humans ; Incidence ; Twins, Monozygotic

OBJECTIVETo evaluate the association of cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) + 49A/G polymorphism with type 1 diabetes mellitus (T1DM) in children.

METHODSPapers about the association of CTLA4+49A/G polymorphism with T1DM in children were collected by searching PubMed, EBSCO, CBM, CNKI, and Wanfang Data. A meta-analysis was performed to examine differences in the genotypes (AG, GG, and GG+AG) and G allele at position 49 of the CTLA-4 gene between a childhood T1DM group and a control group.

RESULTSA total of 10 papers involving 1084 T1DM children and 1338 healthy children were included. The Meta-analysis was performed to evaluate the association of the genotypes (AG, GG, and GG+AG) and the G allele at position 49 of the CTLA-4 gene with T1DM using a fixed effect model according to the heterogeneity test results of all studies. The pooled OR values (95% CI) were 1.13 (0.97-1.33), 1.42 (1.16-1.75), 1.20 (1.03-1.40), and 1.21 (1.09-1.33), suggesting a significant difference in genotypes (AG, GG, and GG+AG) and the G allele at position 49 of the CTLA-4 gene between the two groups.

CONCLUSIONSCTLA-4 +49A/G polymorphism is associated with T1DM in children.

CTLA-4 Antigen ; genetics ; Diabetes Mellitus, Type 1 ; genetics ; Genotype ; Humans ; Polymorphism, Genetic

OBJECTIVETo identify the A3243G mutation of mitochondrial (mt) DNA in patients with latent autoimmune diabetes mellitus in adults (LADA) of Han nationality in the northeast area of China.

METHODSSeventy-nine diabetics of Han nationality, whose families have resided in the northeast area of China for more than 3 generations, were divided into 3 groups: Group 1 (22 cases of type 2 diabetes with maternal inheritance history), Group 2 (34 cases of LADA), Group 3 (23 cases of type 1 diabetes in adolescents). The A3243G of mt DNA was detected in these 79 subjects with the method of PCR-RFLP.

RESULTSNone of the 79 diabetics studied was positively identified for the A3243G mutation of mt DNA.

CONCLUSIONThe A3243G mutation of mt DNA might not be related to the onset of LADA in diabetic population of Han nationality in northeast area of China and there might not be close relationship between A3243G mutation of mt DNA and autoimmunity.

Adolescent ; Adult ; Autoimmune Diseases ; genetics ; DNA, Mitochondrial ; genetics ; Diabetes Mellitus, Type 1 ; genetics ; Diabetes Mellitus, Type 2 ; genetics ; Female ; Humans ; Male ; Middle Aged ; Point Mutation

The loss of or decreased functional pancreatic β-cell is a major cause of type 1 and type 2 diabetes. Previous studies have shown that adult β-cells can maintain their ability for a low level of turnover through replication and neogenesis. Thus, a strategy to prevent and treat diabetes would be to enhance the ability of β-cells to increase the mass of functional β-cells. Consequently, much effort has been devoted to identify factors that can effectively induce β-cell expansion. This review focuses on recent reports on small molecules and protein factors that have been shown to promote β-cell expansion.
Cell Communication ; genetics ; Cell Differentiation ; genetics ; Cell Proliferation ; Diabetes Mellitus, Type 1 ; genetics ; pathology ; Diabetes Mellitus, Type 2 ; genetics ; pathology ; Humans ; Insulin-Secreting Cells ; chemistry ; metabolism ; pathology

Autoimmune diabetes is a T cell-mediated disease characterized by the autoimmune destruction of pancreatic β-cells and insulin deficiency. It is related to multiple genes. The IDDM1 locus, which lies within the human leukocyte antigen (HLA) and the IDDM2 locus, which is located to the insulin gene region, are two major genetic contributors of susceptibility. Many other loci conferring susceptibility to autoimmune diabetes are being discovered, including PTPN22, CTLA4, IL2RA and IFIH1. In this article, these loci and their possible immunologic mechanisms involved in the pathogenesis of this disease will be reviewed.
Animals ; Diabetes Mellitus, Type 1 ; genetics ; immunology ; pathology ; Genetic Predisposition to Disease ; Humans

Child ; Diabetes Mellitus, Type 1 ; genetics ; Female ; Humans ; Infant ; Male ; Siblings

OBJECTIVEWolcott-Rallison syndrome (WRS) is a rare autosomal recessive disorder characterized by the association of permanent neonatal or early-infancy insulin-dependent diabetes, multiple epiphyseal dysplasia and growth retardation, and other variable multisystem clinical manifestations. Here we describe a Chinese boy affected by WRS. Genetic testing of his EIF2AK3 gene was performed in order to elucidate molecular variations and subsequently to provide credible genetic counseling for prenatal diagnosis in his family.

METHODBased on analysis of a nine-year-old boy's clinical symptoms associated with biochemical examination and imaging, the diagnosis of WRS was therefore made. Genomic DNAs were extracted from peripheral blood leukocytes from the boy and his parents with their informed consent for genetic studies. All EIF2AK3 exons and intron-exon boundaries were amplified by Touch-down polymerase chain reaction (Touch-down PCR) and sequenced.

RESULTDirect sequencing of PCR products revealed the presence of a heterozygous T insertion (c.1408_1409insT) in exon 8 of the EIF2AK3 gene leading to frameshifting and termination, and another heterozygous T to A exchange (c.1596T > A) in exon 9 of the EIF2AK3 gene resulting in nonsense C532X mutation.

CONCLUSIONCombining mutation screening of EIF2AK3 gene with clinical manifestations and effective examination may provide a reliable diagnostic method for patients. In this research, two novel mutations identified in the Chinese boy locate in the catalytic domain of the EIF2AK3 gene, disrupting the ability of autophosphorylation, leading to the truncated proteins that are unable to phosphorylate the natural substrate, which are responsible for the phenotype of Wolcott-Rallison syndrome.

Child ; Diabetes Mellitus, Type 1 ; genetics ; Epiphyses ; abnormalities ; Humans ; Male ; Mutation ; Osteochondrodysplasias ; genetics ; eIF-2 Kinase ; genetics

Zinc transporter 8 (ZnT8) is an important candidate antigen for type Ⅰ diabetes. The autoantibody detection kit based on ZnT8 can be used to help diagnose type Ⅰ diabetes, and the related products have been launched in Europe and the United States. Since the recombinant production system of active ZnT8 has not been established in China, this key raw material is heavily dependent on imports. We used Saccharomyces cerevisiae to carry out the recombinant expression of ZnT8. First, multiple antigenic forms of ZnT8 were designed as C-terminal haploid (C), C-terminal diploid (C-C), and N-terminal and C-terminal concatemers (N-C). The proteins were expressed, purified and tested for antigenicity by bridging-type ELISA. The serum of 13 patients with type Ⅰ diabetes and the serum of 16 healthy volunteers were detected. C, N-C, and C-C proteins had similar detection rates, which were 53.8% (7/13), 61.5% (8/13) and 53.8% (7/13). The specificity of the three groups was 100% (16/16). The detection value on positive samples P3, P4, and P8 increased by more than 90%, indicating better serum antibody recognition ability. Finally, N-C protein was selected for further serum sample testing, and the test results were characterized by receiver operating characteristic (ROC) curve for sensitivity and specificity. Compared with imported gold standard antigen, the sensitivity was 76.9% (10/13) and the specificity was 87.5% (14/16). There was no significant difference in the sensitivity of the method, but the specificity needed to be improved. In conclusion, the ZnT8 N-terminal and C-terminal concatemer protein developed based on S. cerevisiae expression system is expected to be a key alternative raw material in the development of in vitro diagnostic reagents for type Ⅰ diabetes.
Antigens ; Autoantibodies ; Diabetes Mellitus, Type 1/diagnosis* ; Enzyme-Linked Immunosorbent Assay ; Humans ; Saccharomyces cerevisiae/genetics* ; Zinc Transporter 8/genetics*

Diabetes mellitus is caused by deficiency of insulin secretion from the pancreatic islet beta cells and/or insulin resistance in liver, muscle and adipocytes, resulting in glucose intolerance and hyperglycemia. Several protein tyrosine phosphatases, such as PTP1B (PTPN1), TCPTP (PTPN2), LYP (PTPN22), PTPIA-2, PTPMEG2 (PTPN9) or OSTPTP are involved in insulin signaling pathway, insulin secretion and autoreactive attack to pancreatic beta cells. Genetic mutation or overexpression of these phosphotases has been found to cause or increase the risk of diabetes mellitus. Some population with high risk for type 2 diabetes has overexpressed PTP1B, a prototypical tyrosine phosphatase which down-regulates insulin and leptin signal transduction. Animal PTP1B knockout model and PTP1B specific inhibitor cellular studies indicate PTP1B may serve as a therapeutic target for type 2 diabetes. TCPTP shares more than 70% sequence identity with PTP1B in their catalytic domain. TCPTP dephosphorylates tyrosine phosphorylated substrates overlapping with PTP1B but also has its own distinct dephosphorylation sites and functions. Recent research indicates TCPTP may have role in type 1 diabetes via dysregultaion of cytokine-mediated immune responses or pancreatic beta cell apoptosis. The tyrosine phosphatase LYP, which down-regulates LCK activity in T cell response, can become mutated as R620W which is highly correlated to type 1 diabetes. LYP R620W may be a gain of function mutation which suppresses TCR signaling. Patients bearing the R620W mutant have impaired T cell responses and increased populations of (CD45RO+CD45RA-) CD4+ T cells. A detailed elucidation of mechanism of R620W in type 1 diabetes and specific LYP inhibitor development will help characterize LYP R620W as a therapeutic target. A receptor tyrosine phosphatase, PTPIA-2/beta is a major autoantigen of type 1 diabetes. A diagnosis kit identifying PTPIA-2/beta autoantibodies is valuable in early detection and prevention of type 1 diabetes. In addition, other phosphatase like OSTPTP and PTPMEG2 are involved in type 2 diabetes via regulation of insulin production, beta cell growth or insulin signaling. Research into understanding the mechanism of these tyrosine phosphatases in diabetes, such as their precise functions in the regulation of insulin secretion, the insulin response and the immune response will strengthen our knowledge of diabetes pathophysiology which may result in new diagnostic and therapeutic strategies for diabetes.
Animals ; Diabetes Mellitus ; enzymology ; Diabetes Mellitus, Type 1 ; enzymology ; Diabetes Mellitus, Type 2 ; enzymology ; Humans ; Protein Tyrosine Phosphatase, Non-Receptor Type 1 ; genetics ; metabolism ; Protein Tyrosine Phosphatase, Non-Receptor Type 2 ; genetics ; metabolism ; Protein Tyrosine Phosphatase, Non-Receptor Type 22 ; genetics ; metabolism ; Protein Tyrosine Phosphatases, Non-Receptor ; classification ; genetics ; metabolism