Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0011854 (type 1 diabetes)
 20,749 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The majority of patients with insulin-dependent diabetes (IDDM) have Abs to 40- and/or 37-kDa tryptic fragments (37/40K-Abs) deriving from an unidentified islet cell membrane protein distinct from glutamate decarboxylase (GAD). Recently, autoantibodies against ICA512, which has identity with the protein tyrosine phosphatase-like protein IA2, were reported. In this study we have examined whether IA2/ICA512 is the Ag specificity of 37/40K-Abs, and one of the determinants of islet cell Abs (ICA) detected by immunofluorescence. Serum from 51 of 100 new onset IDDM patients immunoprecipitated 40- and/or 37-kDa insulinoma polypeptides, and 53 immunoprecipitated in vitro translated rIA2; 49 had both 37/40K-Abs and rIA2 Abs. There were strong correlations between the levels of Abs to rIA2 and both 40 kDa (r = 0.85, p < 0.0001) and 37 kDa (r = 0.70, p < 0.0001) insulinoma polypeptides. Trypsin treatment of immunoprecipitated rIA2 yielded 40- and 37-kDa fragments, and preincubation of sera with rIA2 completely inhibited binding to the insulinoma 40- and 37-kDa polypeptides. IA2 Ab levels also correlated with ICA titer in GAD-Ab negative sera, and preincubation with rIA2 reduced ICA staining intensity in sera with ICA and IA2 Abs, but not in sera with ICA in the absence of IA2 Abs. These results provide clear evidence for the identification of IA2/ICA512 as the precursor of the islet 40- and 37-kDa polypeptide autoantigens and as one of the ICA specificities. Combined detection of Abs to IA2 and GAD65 in a single radio-binding assay identified Abs in 88 of 100 IDDM patients, and potentially facilitates population screening for IDDM risk assessment.
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PMID:Identification of protein tyrosine phosphatase-like IA2 (islet cell antigen 512) as the insulin-dependent diabetes-related 37/40K autoantigen and a target of islet-cell antibodies. 759 59

IDDM results from immune-mediated destruction of insulin-producing pancreatic beta-cells in individuals genetically susceptible for the disease. There is evidence that the 65-kDa isoform of GAD plays a critical role in the induction of autoimmune diabetes in NOD mice. In humans, it is still unclear when and to what beta-cell antigens autoreactive lymphocytes become activated during early disease. We conducted a prospective study from birth, BABY-DIAB, among children of mothers with IDDM or gestational diabetes or fathers with IDDM, and we investigated the temporal sequence of antibody responses to islet cells (ICA), insulin (IAA), GAD (GADA), and the protein tyrosine phosphatase IA-2/ICA512 (IA-2A). Of 1,019 children included at birth, we have currently followed 513 to the age of 9 months, 214 to the age of 2 years, and 37 to the age of 5 years. At birth, all antibody specificities were frequent in newborns of diabetic mothers but not fathers and are suggested to be transplacentally acquired because they are strongly correlated with antibody levels in their diabetic mothers. In early childhood, antibody levels were <99th percentile of control subjects in the majority of children. However, 37 children exhibited elevated antibody levels; these were most frequently detected at the age of 2 years. The antibody prevalence at age 2 years was 2.3% for ICA, 7% for IAA, 4.2% for GADA, and 2.8% for IA-2A (8.9% positive for at least one antibody). Children of diabetic fathers were positive for at least one antibody more frequently than were children of diabetic mothers (9 months of age: 8.5 vs. 3.6%; 2 years of age: 16.7 vs. 7.9%). There was no specific sequence in the appearance of positive autoantibodies, but 13 (35%) antibody-positive cases already had more than one ICA before the age of 2 years and 7 (19%) showed reactivity to three islet cell antigens before age 5 years. The presence of multiple antibodies confers high risk for the future development of diabetes; three of six children who exhibited positive antibody responses to all four antibodies tested and another child with two positive antibodies developed clinical diabetes at the ages of 13, 21, and 27 months and 5 years. We conclude that loss of tolerance to beta-cell autoantigens and appearance of autoimmune phenomena occur very early in life in individuals with genetic susceptibility for IDDM. Screening programs to identify candidates for disease-prevention therapies can therefore be focused on this young age-group, in whom the disease process may be less advanced and who may therefore be best suited to such therapies.
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PMID:Perinatal autoimmunity in offspring of diabetic parents. The German Multicenter BABY-DIAB study: detection of humoral immune responses to islet antigens in early childhood. 866 50

Autoimmune processes are involved in pancreatic beta cell destruction in type 1 diabetes. Autoantibodies including islet cell antibodies (ICA), glutamic acid decarboxylase antibodies (GADA), and antibodies directed against protein tyrosine phosphatase/IA2 (IA2-Ab) appear in the circulation years before clinical onset and permit increasingly precise disease prediction. Increasing knowledge of the pathogenesis of type 1 diabetes in animal models and humans suggests that progression to disease is not inevitable in those with indications of autoimmune processes directed against islet beta cells, and that these processes may prove vulnerable to intervention. The conditions therefore exist for screening and attempted intervention in pre-type 1 diabetes. This review will discuss the theoretical and practical background to a major controlled trial using one of a number of interventions currently under consideration. Nicotinamide, a soluble B group vitamin, has for many years been known to protect beta cells against a variety of noxious stimuli. It is at high doses a free radical scavenger, a potent inhibitor of the enzyme poly (ADP-ribose) polymerase (PARP), and prevents depletion of intracellular NAD. Although its benefits have been marginal or absent in recently diagnosed patients, promising pilot studies have been performed in ICA positive first degree relatives and schoolchildren. No serious side effects have been reported from its use at the doses proposed in man or other species. There is therefore a sound case for submitting this agent to a controlled clinical trial, which, in view of the numbers involved, has necessarily been launched on an international collaborative basis.
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PMID:Theory and practice of nicotinamide trials in pre-type 1 diabetes. 888 46

By subtraction strategy and polymerase chain reaction amplification, two novel cDNAs, designated IA-2 and IA-2 beta, were cloned, sequenced and expressed. Both are transmembrane proteins belonging to the protein tyrosine phosphatase family and are expressed in pancreatic islets. Serological studies revealed that a high percentage of patients with IDDM have autoantibodies to IA-2/IA-2 beta and that the presence of these autoantibodies in otherwise normal individuals is highly predictive in identifying those at risk of ultimately developing clinical diabetes. Moreover, many patients who are ICA positive, but who do not have Abs to GAD65, have Abs to IA-2/IA-2 beta. Enzymatic cleavage of IA-2/IA-2 beta and serological analysis showed that IA-2 is the precursor of the 40 kDa tryptic fragment and IA-2 beta is the precursor of the 37 kDa tryptic fragment, both previously shown to be autoantigens. It is concluded that IA-2/IA-2 beta are major autoantigens in IDDM and together with GAD65 are responsible for much of the reactivity of ICA with pancreatic islets. Tests for the detection of autoantibodies to recombinant IA-2/IA-2 beta and recombinant GAD65 are likely to replace the ICA immunofluorescence test for population screening.
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PMID:IA-2 and IA-2 beta are major autoantigens in IDDM and the precursors of the 40 kDa and 37 kDa tryptic fragments. 893 84

Islet antigens associated with type 1 diabetes include a recently identified protein tyrosine phosphatase-like molecule IA-2, which contains the intracellular fragment IA-2ic. To determine whether combinations of antibodies including those to IA-2 characterize and predict type 1 diabetes, we studied antibodies to IA-2, IA-2ic, glutamic acid decarboxylase (GAD65), and islet cell antibodies (ICAs) in 1) 60 newly diagnosed type 1 diabetic patients followed for 1 year, 2) 31 monozygotic twin pairs discordant for type 1 diabetes followed up to 12 years (11 twins developed diabetes), 3) 18 dizygotic twin pairs discordant for type 1 diabetes, and 4) normal healthy control subjects. Newly diagnosed type 1 diabetic patients frequently had antibodies to IA-2 (62%), IA-2ic (67%), GAD65 (77%), and ICAs (85%). The intracellular fragment of IA-2 probably contains the immunodominant epitope as 137 of 143 samples with IA-2 antibodies from type 1 diabetic patients also had IA-2ic antibodies. Monozygotic twins were usually discordant for antibody specificities. Concordance was higher in monozygotic than matched dizygotic twins for both antibody combinations (33 vs. 6%, P < 0.05) and the development of diabetes (33 vs. 0%, P < 0.01). In monozygotic twins, all the antibodies were highly predictive of type 1 diabetes (positive predictive values all >87%), although antibodies were also detected in twins at low risk of disease. In summary, IA-2 emerges as a major antigen associated with type 1 diabetes and distinct from GAD65. Type 1 diabetes-associated autoimmunity, which is probably induced by environmental factors, does not necessarily herald progression to the disease. However, genetic factors may influence the development of combinations of disease-associated antibodies and the progression to type 1 diabetes.
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PMID:Value of antibodies to islet protein tyrosine phosphatase-like molecule in predicting type 1 diabetes. 923 50

Apart from genes in the HLA complex (IDDM1) and the variable number of tandem repeats in the 5' region of the insulin gene (INS VNTR, IDDM2), several other loci have been proposed to contribute to IDDM susceptibility. Recently, linkage and association have been shown between the cytotoxic T lymphocyte-associated protein 4 (CTLA-4) gene on chromosome 2q and IDDM. In a registry-based group of 525 recent-onset IDDM patients <40 years old we investigated the possible interactions of a CTLA-4 gene A-to-G transition polymorphism with age at clinical disease onset and with the presence or absence of established genetic (HLA-DQ, INS VNTR) and immune disease markers (autoantibodies against islet cell cytoplasm (ICA); insulin (IAA); glutamate decarboxylase (GAD65-Ab); IA-2 protein tyrosine phosphatase (IA-2-Ab)) determined within the first week of insulin treatment. In new-onset IDDM patients. G-allele-containing CTLA-4 genotypes (relative risk (RR)= 1.5; 95% confidence interval (CI) = 1.2-2.0; P < 0.005) were not preferentially associated with age at clinical presentation or with the presence of other genetic (HLA-DR3 or DR4 alleles; HLA-DQA1*0301-DQB1*0302 and/or DQA1*0501-DQB1*0201 risk haplotypes; INS VNTR I/I risk genotype) or immune (ICA, IAA, IA-2-Ab, GAD65-Ab) markers of diabetes. For 151 patients, thyrogastric autoantibodies (anti-thyroid peroxidase, anti-thyroid-stimulating hormone (TSH) receptor, anti-parietal cell, anti-intrinsic factor) were determined, but association between CTLA-4 risk genotypes and markers of polyendocrine autoimmunity could not be demonstrated before or after stratification for HLA- or INS-linked risk. In conclusion, the presence of a G-containing CTLA-4 genotype confers a moderate but significant RR for IDDM that is independent of age and genetic or immune disease markers.
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PMID:CTLA-4 gene polymorphism confers susceptibility to insulin-dependent diabetes mellitus (IDDM) independently from age and from other genetic or immune disease markers. The Belgian Diabetes Registry. 935 55

Strategies for assessing risk of progression to IDDM, based on single and combined autoantibody measurement, were evaluated in 2,855 schoolchildren (median age 11.4 years) and 256 children with newly diagnosed IDDM (median age 10.2 years), recruited to a population-based study in the Oxford region. In 256 children with IDDM, levels of antibodies > or =97.5th centile of the schoolchild population were found in 225 (88%) for islet cell antibodies (ICAs), in 190 (74%) for antibodies to GAD, in 193 (75%) for antibodies to protein tyrosine phosphatase IA-2 (IA-2), and in 177 (69%) for autoantibodies to insulin (IAAs). Estimates of risk of progression to IDDM within 10 years, derived by comparing the distribution of antibody markers in the two populations (schoolchildren and children with IDDM), were 6.7% (ICAs), 6.6% (GAD antibodies), 5.6% (IA-2 antibodies), and 4.8% (IAAs) for schoolchildren with levels above the 97.5th centile, increasing to 20, 23, 24, and 11%, respectively, for antibody levels >99.5th centile. Most children with IDDM had multiple antibody markers, and 89% of those diagnosed over age 10 years had > or =2 antibodies above the 97.5th centile, as compared against 0.7% of schoolchildren, in whom this combination gave a 27% 10-year estimated risk of IDDM. Risk increased but sensitivity fell as combined antibody thresholds were raised, or the number of antibodies above the threshold was increased. Strategies based on detection of > or =2 antibodies with primary testing for GAD and IA-2 antibodies and second line testing for ICAs and/or IAAs were evaluated. Detection of at least two markers selected from GAD antibodies > or =97.5th centile and/or IA-2 antibodies > or =99.5th centile and/or ICAs > or =97.5th centile identified 0.25% of schoolchildren and 83% of children with newly diagnosed IDDM, with an estimated risk of 71% (95% CI 57-91). Although confirmation from prospective studies is still needed, this analysis suggests that antibody combinations can predict diabetes in the general population.
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PMID:Prediction of IDDM in the general population: strategies based on combinations of autoantibody markers. 935 15

IA-2 (islet cell Ag 512) and IA-2 beta (phogrin/IAR) are related autoantigens associated with type 1 diabetes. To determine the critical regions for autoantibody binding and which of these autoantigens is the primary target, mutant and chimeric constructs were used to characterize Ab epitope binding in sera from 217 new onset patients with type 1 diabetes and sequential samples from 141 islet cell Ab positive first degree relatives of patients. All 22 relatives and 121 of 129 patients with IA-2/IA-2 beta Abs had reactivity to IA-2-specific epitopes. These epitopes were in the juxtamembrane region (residues 601-682) and the protein tyrosine phosphatase (PTP)-like domain of IA-2. Chimeras showed that IA-2 residues 795-889 were important for IA-2-specific Ab binding in the PTP-like domain, and mutation of IA-2 residues 877 and 911, previously indicated as relevant for phosphatase activity, also reduced Ab binding. In contrast, Ab binding to IA-2 beta was limited to its PTP-like domain, most IA-2 beta Abs recognized epitopes shared with IA-2, and only 20 patients and 2 relatives had Abs to IA-2 beta-specific epitopes. In 4 relatives, IA-2 and/or IA-2 beta Abs developed in follow-up samples. In each of these, Abs to IA-2-specific epitopes were the first detected. In three, spreading to epitopes shared between IA-2 and IA-2 beta in subsequent samples was seen. In the 17 relatives who developed type 1 diabetes, progression to disease was associated with reactivity to multiple IA-2/IA-2 beta epitopes. These data suggest that IA-2 is the primary phosphatase-like autoantigen associated with type 1 diabetes and that studying autoantibody epitope diversity may assist in disease prediction.
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PMID:IA-2 (islet cell antigen 512) is the primary target of humoral autoimmunity against type 1 diabetes-associated tyrosine phosphatase autoantigens. 972 68

Insulin-dependent diabetes mellitus (IDDM) is preceded by the presence of antibodies against islet proteins including a protein tyrosine phosphatase (PTP) designated IA-2. Recently, we cloned a novel PTP named IAR which shares 43% sequence identity with IA-2 and is recognised by antibodies from a majority of patients with IDDM. The aim of the present study was to determine whether IAR antibodies (IAR Ab) or IA-2 antibodies (IA-2 Ab) are associated with progression to IDDM in first-degree relatives "at-risk" for IDDM (operationally defined as those with islet cell antibodies [ICA] > or = 20JDFU or insulin autoantibodies [IAA] > or = 100 nU/ml), and to examine combinations of IAR Ab and IA-2 Ab in these subjects. The sensitivity and specificity of these antibodies were also examined in patients with recent-onset IDDM. Using Cox's Proportional Hazards Model, the number of siblings with IDDM was associated with progression to IDDM in "at-risk" relatives, but other covariables (age, sex, number of affected offspring or parents) were not significantly associated. Using number of affected siblings as a covariable, both IAR and IA-2 antibodies were significantly associated with progression to IDDM (p < 0.005). Combinations of both antibodies, however, did not result in a significantly stronger association with progression to IDDM. The threshold of positivity for IAR Ab (0.5 units) and IA-2 Ab (3.0 units) assays was adjusted to give the same specificity (97.9%) for each assay in 144 healthy control subjects, to allow standardised comparisons. Levels of IAR Ab and IA-2 Ab were strongly correlated in 53 recent-onset IDDM patients (r = 0.70, p < 0.0001) but 11.3% had IAR Ab in the absence of IA-2 Ab and 16.9% had IA-2 Ab in the absence of IAR Ab. The sensitivity for IDDM (defined as the proportion of IDDM patients positive) was 56.6% for IAR Ab and 62.3% for IA-2 Ab. We conclude that there is considerable overlap in IA-2 Ab and IAR Ab positivity, although either antibody can occur independently in IDDM patients. Both IAR Ab and IA-2 antibodies are associated with progression to IDDM in first-degree relatives at-risk of IDDM, but the use of IAR and IA-2 antibodies in combination are not significantly more strongly associated with progression than single antibodies. IAR Ab may play an important role in the prediction of IDDM.
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PMID:Antibodies to the protein tyrosine phosphatases IAR and IA-2 are associated with progression to insulin-dependent diabetes (IDDM) in first-degree relatives at-risk for IDDM. 975 10

Autoimmunity precedes clinical type 1 diabetes, and indicators of maturing autoimmune responses may be useful markers for disease prediction. To study this, epitope maturation of autoantibodies to the related protein tyrosine phosphatase (PTP)-like autoantigens IA-2 and IA-2beta was examined in sequential samples from birth in a cohort of 21 offspring developing multiple islet autoantibodies and a similar cohort of 48 relatives of patients with type 1 diabetes recruited at an older age. Initial reactivity in offspring was heterogeneous against the IA-2 juxtamembrane region (10/21) and PTP domains (13/21), and both specificity and extent of initial IA-2/IA-2beta autoantibodies were associated with HLA class II genotype. Intra-IA-2 epitope spreading and/or intermolecular spreading to IA-2beta epitopes were observed in seven offspring. In contrast, in older relatives, IA-2/IA-2beta Ab reactivity was stable and spreading rare. Development of diabetes in children was associated with the presence of Abs to the IA-2 juxtamembrane region (risk by age 5 yr, 52% vs 0% in those with PTP domain Abs only; p < 0.02), and 5 of 26 relatives who developed diabetes had IA-2 Abs only against the juxtamembrane region. The findings show that autoantibody reactivity to IA-2/IA-2beta is dynamic in the young, show that the juxtamembrane region of IA-2 is an early IA-2 autoantibody target, and suggest that these Abs are a risk factor for development of type 1 diabetes in infancy.
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PMID:Early development and spreading of autoantibodies to epitopes of IA-2 and their association with progression to type 1 diabetes. 986 31


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