Zinc Transporter 8 Autoantibodies Research Articles

ZnT8 autoantibody prevalence is low in youth with type 2 diabetes and associated with higher insulin sensitivity, lower insulin secretion, and lower disposition index

AimZnT8 autoantibody positivity (ZnT8+) is associated with risk for type 1 diabetes and with metabolic complications in adults. Our aim was to assess prevalence of ZnT8 + in the Treatment of T2D in Adolescents and Youth (TODAY) cohort and describe associated phenotypic outcomes. MethodsTODAY participants were 13.98 ± 2.03 years with a confirmed diagnosis of T2D, BMI percentile of 97.69 ± 3.32 (64% female), and GAD- and IA2- at baseline. ZnT8 autoantibodies were measured at baseline and end of study. Results3 of 687 participants (0.29%) were ZnT8 + and there was one conversion (0.15%) from ZnT8- to ZnT8 + during the study. ZnT8A + individuals had higher HbA1c, HDL and LDL cholesterol, and IL-1β concentrations, and lower BMI, IL-6, and triglyceride concentrations compared to the TODAY cohort and ZnT8A- individuals. They also had higher insulin sensitivity with lower insulin secretion and disposition index, metabolically resembling T1D. All ZnT8 + participants experienced loss of glycemic control on randomized treatment, but exhibited lower rates of diabetic complications than other groups. ConclusionGiven the low rate of complications in ZnT8 + individuals, ZnT8 likely does not impact the clinical course of the disease in this population.

Improved diagnosis of type-1 diabetes mellitus using multiplexed autoantibodies ELISA array

Autoantibodies are currently the most robust biomarkers of type 1 diabetes. However, single autoantibody targeted detection is still limited in diabetes diagnosis with poor performance. Here, we develop a multiplexed Array-ELISA assay that can detect five diabetes-related autoantibodies including glutamic acid decarboxylase antibody (GADA), insulinoma antigen 2 antibody (IA-2A), islet cell antibody (ICA), zinc transporter 8 autoantibody (ZnT8-A) and insulin antibody (IAA) simultaneously. This assay achieved 100% accuracy in identifying the positive and negative control samples with good repeatability (CV<15%). We applied the Array-ELISA assay to 140 clinical serum samples of healthy subjects and diabetes patients and the assay showed improved diagnosis accuracy (sensitivity of 62.5%, specificity of 94.3%) compared with the single target immunoblotting test. These data suggest that the Array-ELISA assay can provide diagnostic and predictive ability in the clinical practice of type 1 diabetes.

Epidemiology and phenotypes of diabetes in children and adolescents in non-European-origin populations in or from Western Pacific region.

BACKGROUNDType 1 diabetes (T1D) incidence varies substantially between countries/ territories, with most studies indicating increasing incidence. In Western Pacific region (WPR), reported rates are much lower than European-origin populations. In contrast, there are reports of substantial numbers of young people with type 2 diabetes (T2D). A deeper understanding of T1D and T2D in the WPR may illuminate factors important in pathogenesis of these conditions. Furthermore, with varying resources and funding for diabetes treatment in this region, there is a need to more clearly determine the current burden of disease and also any gaps in knowledge.AIMTo compile and summarise published epidemiologic and phenotypic data on childhood diabetes in non-European populations in and from WPR.METHODSResearch articles were systematically searched from PubMed (MEDLINE), Embase, Cochrane library, and gray literature. Primary outcome measures were incidence and prevalence, with secondary measures including phenotypic descriptions of diabetes, including diabetes type categorization, presence of diabetic ketoacidosis (DKA) at onset, autoantibody positivity, C-peptide levels, and human leucocyte antigen phenotype. Extracted data were collected using a customized template. Three hundred and thirty relevant records were identified from 16 countries/territories, with analysis conducted on 265 (80.3%) records published from the year 2000.RESULTST1D incidence ranged from < 1-7.3/100000 individuals/year, rates were highest in emigrant/ mixed populations and lowest in South-East Asia, with most countries/territories (71.4%) having no data since 1999. Incidence was increasing in all six countries/territories with data (annual increases 0.5%-14.2%, highest in China). Peak age-of-onset was 10-14 years, with a female case excess. Rate of DKA at onset varied from 19.3%-70%. Pancreatic autoantibodies at diagnosis were similar to European-origin populations, with glutamic acid decarboxylase-65 autoantibody frequency of 44.1%-64.5%, insulinoma-associated 2 autoantibody 43.5%-70.7%, and zinc transporter-8 autoantibody frequency 54.3% (one study). Fulminant T1D also occurs. T2D was not uncommon, with incidence in Japan and one Chinese study exceeding T1D rates. Monogenic forms also occurred in a number of countries.CONCLUSIONT1D is less common, but generally has a classic phenotype. Some countries/ territories have rapidly increasing incidence. T2D is relatively common. Registries and studies are needed to fill many information gaps.

Practical Clinical Applications of Islet Autoantibody Testing in Type 1 Diabetes.

The distinction between type 1 diabetes (T1D) and type 2 diabetes (T2D) is extremely important for the choice of therapy, body weight and dietary management, screening for coexistent autoimmune diseases and comorbidities, anticipated prognosis, and risk assessment in relatives. Not uncommonly, the presentation of the patient may not allow an unambiguous discrimination between T1D and T2D. To help resolve this challenge, the detection of islet autoantibodies can support the diagnosis of T1D. The presence of islet autoantibodies in a person with diabetes indicates an autoimmune etiology therefore establishing the diagnosis of T1D. Presently 5 islet autoantibodies are available for routine clinical use: islet cell cytoplasmic autoantibodies (ICA), insulin autoantibodies (IAA), glutamic acid decarboxylase autoantibodies (GADA), insulinoma associated-2 autoantibodies (IA-2A), and zinc transporter-8 autoantibodies (ZnT8A). There are caveats to the selection of which islet autoantibodies should be measured. Islet autoantibodies can also predict the development of T1D. Therefore, once safe and effective therapies are available to prevent T1D, islet autoantibody testing is expected to become a routine part of medical practice. A very rare cause of autoimmune diabetes is the type B insulin resistance syndrome resulting from antagonistic autoantibodies to the insulin receptor. Rarely hypoglycemia can result from agonistic insulin receptor autoantibodies, or high-titer IAA causing the autoimmune insulin syndrome (i.e., Hirata disease). In summary, autoimmune causes of dysglycemia are increasing in clinical importance requiring the scrutiny of laboratorians. The determination of islet autoantibodies can greatly aid in the diagnosis and the prediction of T1D.

Screening Strategy for Islet Autoantibodies in Diabetes Patients of Different Ages.

Background: The detection of islet autoantibodies is essential for the accurate classification and diagnosis of diabetes mellitus (DM). The islet autoantibody distribution varies by age. However, screening strategies for DM patients with different onset ages remain lacking. Materials and Methods: This cross-sectional study included 17,536 DM patients from 46 medical centers across China. The seroprevalence of glutamic acid decarboxylase autoantibody (GADA), insulinoma-associated-2 autoantibody (IA-2A), zinc transporter 8 autoantibody (ZnT8A), and insulin autoantibody (IAA) was determined in younger and older patients with type 1 DM (T1DM) (n = 287 and 285, respectively), younger and older patients with latent autoimmune diabetes (LAD) (n = 140 and 121, respectively), and younger and older patients with type 2 DM (n = 200 in each group). Results: The cutoff age between younger and older patients was 35 years using restricted cubic spline method (n = 17,536, adjusted R2 = 0.97, residual standard error = 1.32; P < 0.001). The seroprevalence rates of four islet autoantibodies were higher in patients aged 15-35 years than in those ≥35 years (GADA: 17% vs. 5.6%, IA-2A: 8.5% vs. 1.3%, ZnT8A: 6.3% vs. 2.3%, IAA: 2.2% vs. 1.0%). The prevalence of ZnT8A was higher in LAD patients than in T1DM patients, especially in older LAD patients. The results indicated that ZnT8A detection can increase the detection rate of older LAD patients from 70.2% (based on GADA detection alone) to 91.7%. Conclusions: In patients stratified according to the cutoff age of 35 years, the optimal detection sequence should be GADA, IA-2A, and ZnT8A in younger patients and GADA, ZnT8A, and IA-2A in older patients, so as to reduce the screening cost while improving the detection rate. Particularly, the ZnT8A test is recommended in older patients to avoid a missed LAD diagnosis.

Persistence of islet autoantibodies after diagnosis in type 1 diabetes.

The presence of islet autoantibodies remains a reliable biomarker to identify individuals at high risk of developing type 1 diabetes. As such, these autoantibodies play a pivotal role in understanding the prodrome of diabetes and selecting individuals for both prevention and intervention clinical trials. Over the last few decades, studies have sought to investigate autoantibody prevalence after diabetes onset to better understand ongoing islet autoimmunity; however, many findings are contradictory, and little is known about factors that may influence autoantibody persistence. Generally, glutamate decarboxylase autoantibodies (GADAs) are the most prevalent autoantibodies after diagnosis, particularly in adults, whilst zinc transporter 8 autoantibodies (ZnT8A) prevalence declines more rapidly. However, when studies with islet autoantibody data at diagnosis are considered, it becomes clear that overall islet antigen-2 autoantibodies (IA-2A) tend to persist for longer than GADA or ZnT8A. In this review, we assess the major studies that have contributed to our understanding of autoantibody persistence after diabetes onset and what factors affect this. Islet autoantibodies may provide biomarkers for long-term β-cell function and insights into how to prevent ongoing islet autoimmunity but larger studies collecting samples at and decades after diabetes onset are required to leverage the information they could provide.

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.

High-affinity ZnT8 Autoantibodies by Electrochemiluminescence Assay Improve Risk Prediction for Type 1 Diabetes.

ContextSingle ZnT8 autoantibody (ZnT8A) positivity by standard radiobinding assay (RBA) is commonly seen in nondiabetes population-based screening and the risk of progression to type 1 diabetes (T1D) in subjects with single ZnT8A is unknown.ObjectiveIdentify the risk of progression to T1D in individuals positive only for ZnT8A.MethodsWe developed an electrochemiluminescence (ECL) assay to detect high-affinity ZnT8A and validated it in 3 populations: 302 patients newly diagnosed with T1D, 135 nondiabetic children positive for ZnT8A by RBA among 23 400 children screened by the Autoimmunity Screening for Kids (ASK) study, and 123 nondiabetic children multiple autoantibody positive or single ZnT8A positive by RBA participating in the Diabetes Autoimmunity Study in the Young (DAISY).ResultsIn 302 patients with T1D at diagnosis, the positivity for ZnT8A was 62% both in RBA and ECL. Among ASK 135 participants positive for RBA-ZnT8A, 64 were detected ZnT8A as the only islet autoantibody. Of these 64, only 9 were confirmed by ECL-ZnT8A, found to be of high affinity with increased T1D risk. The overall positive predictive value of ECL-ZnT8A for T1D risk was 87.1%, significantly higher than that of RBA-ZnT8A (53.5%, P < .001). In DAISY, 11 of 2547 children who had no positivity previously detected for other islet autoantibodies were identified as single ZnT8A by RBA; of these, 3 were confirmed positive by ECL-ZnT8A and all 3 progressed to clinical T1D.ConclusionA large proportion of ZnT8A by RBA are single ZnT8A with low T1D risk, whereas ZnT8A by ECL was of high affinity and high prediction for T1D development.

Zinc transporter 8 (ZnT8) autoantibody prevalence in black South African participants with type 1 diabetes

BackgroundAutoantibodies to β-cell specific antigens are markers of type 1 diabetes. The most recently identified autoantibodies are targeted to the zinc transporter 8 (ZnT8) protein located in the membrane of β-cell insulin secretory granules. The prevalence of ZnT8 autoantibodies in newly diagnosed participants with type 1 diabetes has been found to range from 33 to 80 %. Due to the lack of data on the immunological aetiology of type 1 diabetes in African populations, this study aimed to determine the prevalence of ZnT8 autoantibodies in black South Africans with type 1 diabetes and whether ZnT8 autoantibody positivity was associated with age at diagnosis and disease duration.MethodsParticipants with type 1 diabetes and controls were recruited from the greater Johannesburg area, South Africa. Positivity for ZnT8, GAD65 and IA2 autoantibodies was determined by ELISA.ResultsParticipants with type 1 diabetes (n = 183) and controls (n = 49) were matched for age (29.1 ± 9.53 vs. 27.3 ± 7.29, respectively; p = 0.248). The mean age at diagnosis for participants with type 1 diabetes was 20.8 ± 8.46 years. The prevalence of ZnT8 autoantibody positivity was 17.5 % (32 of 183) in participants with type 1 diabetes with a median disease duration of 7.00 [2.00; 11.0] years. ZnT8 autoantibody prevalence in newly diagnosed participants (< 1 year duration) was 27.3 % (6 of 22). Logistic regression analysis found an association between ZnT8 autoantibody positivity and shorter disease duration (OR: 0.9 (0.81-1.00); p = 0.042). In addition, ZnT8 autoantibody positivity was significantly associated with an increased chance of being GAD65 (OR: 3.37 (1.10–10.3)) and IA2 (OR: 8.63 (2.82–26.4)) autoantibody positive. Multiple regression analysis found no association between ZnT8 autoantibody positivity and age at diagnosis. However, the presence of ≥ 2 autoantibodies was associated with a younger age at diagnosis of type 1 diabetes when compared to participants with ≤ 1 autoantibody (B = -5.270; p = 0.002).ConclusionsThe presence of ZnT8 autoantibodies was not related to a younger age at diagnosis in black South African patients with type 1 diabetes. However, the greater the numbers of autoantibodies present in an individual the earlier the age at diagnosis. ZnT8 autoantibodies decline with disease duration in the black South African population.

159-LB: High-Affinity ZnT8 Autoantibodies by Electrochemiluminescence Assay Improve the Risk Prediction for Type 1 Diabetes

Background: A cohort of children with single ZnT8 autoantibody (ZnT8A) positivity were identified in two large clinical trials, Autoimmunity Screening for Kids (ASK) and Diabetes Autoimmunity Study in the Young (DAISY), and their risk of type 1 diabetes (T1D) have never been studied. Methods: Three cohorts were analyzed using a high-affinity electrochemiluminescence (ECL) ZnT8A assay including 302 new onset T1D patients, 135 children positive for ZnT8A by standard radio-binding assay (RBA) from 23400 children screened in ASK study, and 123 children with multiple autoantibodies or single ZnT8A by RBA from 2547 children in DAISY study. Results: ECL-ZnT8A had a similar sensitivity with RBA-ZnT8A in the cohort of 302 new onset T1D patients (62.3% vs. 61.9%). In ASK, 135/23400 of general population children were positive for RBA-ZnT8A and 64/135 were found as single ZnT8A only without other islet autoantibodies. Of 64 children with single ZnT8A, only 14.1% (9/64) were detectable by ECL-ZnT8A. Antibody-affinity analysis revealed that the ZnT8A in RBA but not confirmed by ECL were of low affinity and they were easily disappeared during the follow-up behaving as ‘transient’ positivity. In terms of T1D classification from stage 1 to stage 3, positive predictive value (PPV) of ECL-ZnT8A (61/70 [87.1%]) was significantly higher than that of RBA-ZnT8A (73/137 [53.3%]; P&amp;lt;0.0001). The cumulative risk of clinical T1D development with ZnT8A confirmed by ECL (16/66) was significantly enhanced during a short time of follow-up, compared with ZnT8A not confirmed by ECL (1/43; p=0.023). Similarly in DAISY participants, 11/2547 children were identified as single ZnT8A by RBA while only three who developed T1D were detected ECL-ZnT8A. Conclusions: Large proportion of ZnT8A by current standard RBA are single ZnT8A with majority at low risk in population-based screening while ECL-ZnT8A can discriminate high risk from low risk and are highly predictive for T1D development. Disclosure X. Jia: None. L. He: None. D. Miao: None. K. Waugh: None. C. Geno rasmussen: None. F. Dong: None. M. Rewers: Advisory Panel; Self; Provention Bio, Inc., Consultant; Self; RTI, Research Support; Self; Janssen Research &amp; Development, LLC, JDRF. L. Yu: None. Funding Diabetes Research Center (P30DK116073); JDRF (2-SRA-2018-533-S-B, 2-SRA-2020-965-S-B, 1-SRA-2016-208-S-B); National Institutes of Health (DK32083)

78-OR: Aß Classification in Children with New-Onset Diabetes

The current binary classification (T1D vs. T2D) is inadequate to comprehensively dissect the heterogeneity of pediatric diabetes. The Aβ classification system, based on presence of islet autoimmunity (A+ or A-) and beta-cell functional reserve (β+ or β-), has been validated to define distinct phenotypic forms of Ketosis-Prone Diabetes in adults. Here, we aimed to study the utility of the Aβ classification system in children with new-onset diabetes. “A+” was defined as presence of ≥1 islet autoantibodies (GAD65, ICA512, insulin and ZnT8 autoantibodies) and “β+” as random C-peptide level ≥0.6 ng/mL at diagnosis. We compared the clinical characteristics at diabetes onset between the groups. The study cohort (n=67) was 46% female, 33% non-Hispanic white, 43% Hispanic, 21% non-Hispanic black and 3% Other. Mean age was 11.2 years and mean BMI was 59.3%ile. Aβ classification at diagnosis defined the following groups: A+β- (43%), A+β+ (24%) and A-β+ (33%). There were no A-β- patients. Median C-peptide levels in the three groups were 0.3, 0.7 and 3.3 ng/mL, respectively. Mean BMI %iles were 34.4 in A+β-, 53.1 in A+β+, and 96.4 in A-β+ group (p&amp;lt;0.001). A-β+ group were older (14 y/o) compared to A+β- (8.9 y/o) and A+β+ (11.7 y/o) (p&amp;lt;0.001). Diabetic ketoacidosis at diabetes onset was most frequent in A+β- (69%), intermediate in A+β+ (44%) and least in A-β+ (18%) (p&amp;lt;0.01). Hispanic ethnicity was more common in A-β+ (64%) compared to A+β+ (44%) and A+β- (28%) (p=0.03). There were no significant differences in sex, mean HbA1c and daily insulin dose per kg at diabetes diagnosis between the groups. The Aβ classification system provides more pathophysiologic insight and discrimination of characteristics than the current classification system. The A-β- group, which we previously reported to be 2.6% of a large pediatric diabetes cohort, was not represented in this smaller study. If prospective follow-up confirms distinct natural histories for these groups, the Aβ classification will be useful in clinical practice and for the design of intervention trials. Disclosure M. Tosur: Advisory Panel; Self; Provention Bio, Inc. S. Deen: None. S. Uysal: None. M. Astudillo: None. F. Jahoor: None. M. J. Redondo: Advisory Panel; Self; Provention Bio, Inc. A. Balasubramanyam: None. Funding Texas Children’s Hospital

Autoimmune thyroid disease correlates to islet autoimmunity on zinc transporter 8 autoantibody.

ObjectiveThe most common coexisting organ-specific autoimmune disease in patients with type 1 diabetes mellitus (T1DM) is autoimmune thyroid disease (AITD). However, there have been few clinical reports based on a large population about the prevalence of zinc transporter 8 autoantibody (ZnT8A) and other islet autoantibodies in AITD patients. We aimed to explore the presence of islet autoantibodies, ZnT8A, glutamic acid decarboxylase autoantibodies (GADA) and insulinoma-associated antigen 2 autoantibodies (IA-2A) compared with thyroid autoantibodies, thyroid peroxidase autoantibodies (TPOAb) and thyroglobulin autoantibodies (TGAb) and thyrotropin receptor autoantibodies (TRAb) in patients with Graves’ disease (GD), Hashimoto’s thyroiditis (HT) and T1DM patients with AITD.MethodsTotally, 389 patients with GD, 334 patients with HT, 108 T1DM patients with AITD and 115 healthy controls (HC) were recruited in the study. Islet autoantibodies (ZnT8A, GADA and IA-2A) were detected by radioligand binding assay. Thyroid autoantibodies, TPOAb and TGAb were detected by chemiluminescence assay, and TRAb was detected by RIA.ResultsThe prevalence of ZnT8A, GADA and IA-2A was higher in GD and HT patients than that of HC (ZnT8A: GD 8.48%, HT 10.8% vs HC 1.74%; GADA: GD 7.46%, HT 7.74% vs HC 0.870%; IA-2A: GD 4.88%, HT 3.59% vs HC 0%; All P < 0.05) but lower than that of T1DM subjects with AITD (ZnT8A: 42.6%; IA-2A: 44.4%; GADA: 74.1%; all P < 0.0001).ConclusionsAn increased prevalence of ZnT8A as well as GADA and IA-2A was found in both GD and HT patients, indicating that there is a potential link between thyroid autoimmunity and islet autoimmunity.

The establishment and application of testing methods of tetraspanin 7 autoantibody in type 1 diabetes

Objective: To establish the luciferase immunoprecipitation system assay (LIPS) to test tetraspanin 7 autoantibody (TSPAN7A) and evaluate its value in Chinese type 1 diabetes (T1D) patients. Methods: Renilla luciferase-tagged TSPAN7 plasmids were transfected into 293T cells to obtain Renilla luciferase-tagged TSPAN7 fusion protein. The cell lysate was incubated with sera overnight, followed by addition of protein A-agarose and extensive wash. Finally, the substrate of Renilla luciferase was added and luminescence was detected. Sera from 100 T1D patients [64 males and 36 females,with a mean age of (28±16) years], 119 type 2 diabetes (T2D) patients [78 males and 41 females,with a mean age of (47±12) years] and 98 healthy volunteers [55 males and 43 females,with a mean age of (28±12) years] from the Department of Metabolism and Endocrinology of the Second Xiangya Hospital, Central South University from 2014 to 2017, were tested by LIPS to evaluate the frequency of TSPAN7A. Radioligand binding assay (RLA) was used to test glutamic acid decarboxylase autoantibodies (GADA), protein tyrosine phosphatase-2 autoantibodies (IA-2A) and zinc transporter 8 autoantibodies (ZnT8A). Results: The frequencies of GADA, IA-2A, ZnT8A and TSPAN7A in T1D patients were 72.0%, 40.0%, 29.0% and 25.0%, respectively. After Bonferroni correction, the positivity of TSPAN7A was lower than GADA (P<0.001), but similar with IA-2A (P=0.035) and ZnT8A (P=0.630). The positivity of TSPAN7A in T1D patients was significantly higher than that in T2D (0.84%, P<0.001) and in healthy controls (1.02%, P<0.001). In combination with TSPAN7A, the positivity of islet autoantibodies in T1D patients increased from 82% to 85%. There was no significant difference in clinical characteristics between TSPAN7A-positive T1D and the other three islet autoantibodies-positive patients. Conclusion: This study succeeded in establishing LIPS method to assay TSPAN7A. Moreover, TSPAN7A are valid islet autoantibodies for T1D patients in China.

Genetic Composition and Autoantibody Titers Model the Probability of Detecting C-Peptide Following Type 1 Diabetes Diagnosis.

We and others previously demonstrated that a type 1 diabetes genetic risk score (GRS) improves the ability to predict disease progression and onset in at-risk subjects with islet autoantibodies. Here, we hypothesized that GRS and islet autoantibodies, combined with age at onset and disease duration, could serve as markers of residual β-cell function following type 1 diabetes diagnosis. Generalized estimating equations were used to investigate whether GRS along with insulinoma-associated protein-2 autoantibody (IA–2A), zinc transporter 8 autoantibody (ZnT8A), and GAD autoantibody (GADA) titers were predictive of C-peptide detection in a largely cross-sectional cohort of 401 subjects with type 1 diabetes (median duration 4.5 years [range 0–60]). Indeed, a combined model with incorporation of disease duration, age at onset, GRS, and titers of IA–2A, ZnT8A, and GADA provided superior capacity to predict C-peptide detection (quasi-likelihood information criterion [QIC] = 334.6) compared with the capacity of disease duration, age at onset, and GRS as the sole parameters (QIC = 359.2). These findings support the need for longitudinal validation of our combinatorial model. The ability to project the rate and extent of decline in residual C-peptide production for individuals with type 1 diabetes could critically inform enrollment and benchmarking for clinical trials where investigators are seeking to preserve or restore endogenous β-cell function.

High-Affinity ZnT8 Autoantibodies by Electrochemiluminescence Assay Improve the Risk Prediction for Type 1 Diabetes

Background: A cohort of children with single ZnT8 autoantibody (ZnT8A) positivity were identified in two large clinical trials, Autoimmunity Screening for Kids (ASK) and Diabetes Autoimmunity Study in the Young (DAISY), and their risk of type 1 diabetes (T1D) have never been studied. Methods: Three cohorts were analyzed using a high-affinity electrochemiluminescence (ECL) ZnT8A assay including 302 new onset T1D patients, children with positive ZnT8A (n=135) by radio-binding assay (RBA) from 23400 general population children screened in the ASK study, and children (n=123) with multiple islet autoantibodies (IAbs) or single ZnT8A by RBA identified from 2547 longitudinally followed cases in DAISY. In addition, 1098 samples with all IAbs negative were also analyzed for ECL-ZnT8A. Findings: In ASK study, 0.58% (135/23400) of children were detected ZnT8A by RBA and 47.4% (64/135) of these ZnT8A were unexpectedly found as ZnT8A alone. Of 64 children with single ZnT8A, only 9 were detectable by ECL-ZnT8A. ZnT8A by RBA not confirmed by ECL were found low affinity with low risk. Positive predictive value of ECL-ZnT8A, in terms of high risk from T1D stage 1 to stage 3, was significantly higher (P<0.0001) than that of RBA-ZnT8A. Similarly in 2547 children of DAISY cohort, 11 cases in total were identified as single ZnT8A while only three who developed clinical T1D were detected ECL-ZnT8A. Interpretation: Majority of single ZnT8A positivity detected in screening by RBA were of low affinity with low T1D risk while ZnT8A detected by ECL assay were of high-affinity with high prediction for T1D development. Funding: JDRF, NIH Declaration of Interests: The authors declare no conflict of interest related to this study. Ethics Approval Statement: All subjects were provided written or electronic informed consent and all studies were approved by the University of Colorado Institutional Review Board.

Autoantibodies against zinc transporter 8 further stratify the autoantibody-defined risk for type 1 diabetes in a general population of schoolchildren and have distinctive isoform binding patterns in different forms of autoimmune diabetes: results from the Karlsburg Type 1 Diabetes Risk Study.

To evaluate the diagnostic relevance of autoantibodies against zinc transporter 8 (ZnT8) in schoolchildren from the general population as well as in people with autoimmune diabetes. A total of 137 schoolchildren positive for at least one of the three major diabetes-associated autoantibodies, without diabetes heredity or preselection on HLA typing, from the Karlsburg Type 1 Diabetes Risk Study, as well as 102 people at type 1 diabetes onset, 88 people with latent autoimmune diabetes in adults and 119 people with type 2 diabetes, were analysed for different ZnT8 autoantibody variants. Zinc transporter 8 autoantibody positivity was found in 18% of autoantibody-positive schoolchildren, with a noticeable association with other autoantibodies associated with type 1 diabetes and disease progression. Furthermore, ZnT8 autoantibody positivity was associated with diabetes progression in schoolchildren positive for autoantibodies against insulinoma-associated antigen-2 (IA-2) and, importantly, in seven IA-2 autoantibody-negative schoolchildren. Additionally, ZnT8 autoantibodies were found in 56% of people with type 1 diabetes, predominantly directed against all three ZnT8 variants and comparable to schoolchildren with multiple autoantibodies. In contrast, ZnT8 autoantibodies were detected in 10% of people with latent autoimmune diabetes in adults, none of them with reactivity to all three isoforms. Zinc transporter 8 autoantibodies are useful markers for prediction of type 1 diabetes in a general population, further stratifying the risk of progression in autoantibody-positive children. ZnT8 autoantibodies are also important markers in adult-onset diabetes, with a completely different reaction pattern in type 1 diabetes in comparison to latent autoimmune diabetes in adults, and may therefore help to differentiate between the two forms.

Zinc transporter 8 autoantibody in the diagnosis of type 1 diabetes in children.

Background Type 1 diabetes (T1D) is an organ-specific autoimmune disease related to the autoimmune response against pancreatic β-cells. Zinc transporter 8 (ZnT8), an islet-specific gene product localized to the β-cell insulin granule, was recently identified as an autoantigen in T1D.Purpose To evaluate the use of ZnT8 autoantibody (ZnT8A) for diagnosing T1D.Methods This case-control study was conducted at Dr. Soetomo General Hospital, Surabaya, Indonesia, from March to May 2019. Children younger than 18 years of age with T1D based on the International Society for Pediatric and Adolescent Diabetes guideline and healthy controls were included. We measured ZnT8A level using enzyme-linked immunosorbent assay (cutoff value, 0.315).Results There were 30 children with T1D (50.0% boys; mean age, 11.3±3.7 years) and 18 healthy controls (44.4% boys; mean age, 8.3±3.1 years); 1 patient in each group was Madurese, while the others were Javanese. Twenty-two of 30 subjects with T1D (73.3%) tested positive for ZnT8A compared to 5 of 18 controls (27.8%) (P=0.02; odds ratio, 7.15; 95% confidence interval, 1.93–26.52). When ZnT8A-positive and -negative T1D cases were compared, no differences were detected in age at diagnosis, duration of diabetes, presence of ketoacidosis, body mass index, glycosylated hemoglobin concentration, or C-peptide concentrations.Conclusion ZnT8A may be useful in the diagnosis of T1D.

Dynamics of Islet Autoantibodies During Prospective Follow-Up From Birth to Age 15 Years.

ContextWe set out to characterize the dynamics of islet autoantibodies over the first 15 years of life in children carrying genetic susceptibility to type 1 diabetes (T1D). We also assessed systematically the role of zinc transporter 8 autoantibodies (ZnT8A) in this context.DesignHLA-predisposed children (N = 1006, 53.0% boys) recruited from the general population during 1994 to 1997 were observed from birth over a median time of 14.9 years (range, 1.9-15.5 years) for ZnT8A, islet cell (ICA), insulin (IAA), glutamate decarboxylase (GADA), and islet antigen-2 (IA-2A) antibodies, and for T1D. ResultsBy age 15.5 years, 35 (3.5%) children had progressed to T1D. Islet autoimmunity developed in 275 (27.3%) children at a median age of 7.4 years (range, 0.3-15.1 years). The ICA seroconversion rate increased toward puberty, but the biochemically defined autoantibodies peaked at a young age. Before age 2 years, ZnT8A and IAA appeared commonly as the first autoantibody, but in the preschool years IA-2A– and especially GADA-initiated autoimmunity increased. Thereafter, GADA-positive seroconversions continued to appear steadily until ages 10 to 15 years. Inverse IAA seroconversions occurred frequently (49.3% turned negative) and marked a prolonged delay from seroconversion to diagnosis compared to persistent IAA (8.2 vs 3.4 years; P = .01).ConclusionsIn HLA-predisposed children, the primary autoantibody is characteristic of age and might reflect the events driving the disease process toward clinical T1D. Autoantibody persistence affects the risk of T1D. These findings provide a framework for identifying disease subpopulations and for personalizing the efforts to predict and prevent T1D.

Evaluation for type 1 diabetes associated autoantibodies in diabetic and non-diabetic Australian terriers and Samoyeds

BackgroundEvidence for an autoimmune etiology in canine diabetes is inconsistent and could vary based on breed. Previous studies demonstrated that small percentages of diabetic dogs possess autoantibodies to antigens known to be important in human type 1 diabetes, but most efforts involved analysis of a wide variety of breeds. The objective of this study was to evaluate the presence of glutamic acid decarboxylase 65 (GAD65), insulinoma-associated protein 2 (IA-2), and zinc transporter 8 (ZnT8) autoantibodies in diabetic and non-diabetic Australian Terriers and Samoyeds, two breeds with comparatively high prevalence of diabetes, in the United States.ResultsThere was no significant difference in the proportion of samples considered positive for GAD65 or ZnT8 autoantibodies in either breed evaluated, or for IA-2 autoantibodies in Australian Terriers (p > 0.05). The proportion of IA-2 autoantibody positive samples was significantly higher in diabetic versus non-diabetic Samoyeds (p = 0.003), but substantial overlap was present between diabetic and non-diabetic groups.ConclusionsThe present study does not support GAD65, IA-2, or ZnT8 autoantibodies as markers of autoimmunity in canine diabetes in Samoyeds or Australian Terriers as measured using human antigen sandwich enzyme-linked immunosorbent (ELISA) assays. Future studies using canine specific assays as well as investigation for alternative markers of autoimmunity in these and other canine breeds are warranted.

Prevalence of diabetes-associated autoantibodies among patients presenting with type 2 diabetes and related metabolic differences

BackgroundTo explores the prevalence of autoantibodies (zinc transporter 8 autoantibodies (ZnT8A), antibodies to insulin (IAAs), glutamic acid decarboxylase autoantibody (GAD65)), the relation of the type of positive autoantibody and the number of positive autoantibodies with the glycemic and lipid profile of the patients with LADA (Latent Autoimmune Diabetes in Adults) and compares it to the metabolic profile of patients presenting with type 2 diabetes (T2DM). Methods263 patients with T2DM were recruited for this cross-sectional study in Tehran, Iran. Data from patients included complete medical history, GAD65, ZnT8A, IAA and routine metabolic laboratory workup. Assay for autoantibodies were conducted using ELISA kits. The association between autoantibodies and glycemic and lipid profile of patients with diabetes was assessed using univariate and multivariate regression analysis. ResultsOur study revealed that among 263 patients with T2DM, 29 (11%) cases were positive for IAAs, 9 (3.4%) for ZnT8A, and 12 (4.6%) for GAD65. Six (2.3%) of the patients had triple positive antibodies. Patients with positive results were younger, had lower body mass index (BMI), c-peptide, triglyceride, low-density lipoprotein (LDL), and higher high-density lipoprotein (HDL), HbA1c and fasting blood glucose (FBG) levels. Triple antibody positivity was significantly associated with lower levels of C-Peptide, Triglycerides, FBG, and HbA1c compared to triple negative antibodies. ConclusionPatients with LADA positive for either of the autoantibodies (GAD65, ZnT8 and IAA) presented with worse glycemic control. Measurement of these autoantibodies can assist in discrimination of these patients and help with earlier control of glycemic profile.