Zinc transporter-8 autoantibodies can replace IA-2 autoantibodies as a serological marker for juvenile onset type 1 diabetes in India

Characterisation of islet antibody-negative type 1 diabetes mellitus in Indian children

AIMS

Islet antibody-negative type 1 diabetes mellitus (T1DM) has not been well characterised. We determined the frequency of antibody-negative T1DM and compared it with antibody-positive T1DM in a cohort of north Indian children.

METHODS

In a multi-centre, prospective, observational study, 176 Indian children (age 1-18 years) were assessed within 2 weeks of diagnosis of T1DM. Antibodies against GAD65 (GADA), islet antigen-2 (IA-2A) and zinc transporter 8 (ZnT8A), were estimated using validated ELISA. HLA-DRB1, DQA1 and DQB1 alleles were studied by Luminex-based typing. Monogenic diabetes was determined by targeted next-generation sequencing using the Illumina platform.

RESULTS

After excluding 12 children with monogenic diabetes, GADA, IA-2A and ZnT8A were present in 124 (76%), 60 (37%) and 62 (38%) children, respectively, while 24 (15%) were negative for all antibodies. A single antibody (most frequently GADA) was present in 68 (41%) of children, while all three antibodies were found in 34 (21%). Islet antibody-negative T1DM (n = 24, 15%) did not differ from antibody-positive children in their clinical features, HbA1c or plasma C-peptide, both at onset or after 1 year follow-up (available in 62 children). The frequency of other organ-specific antibodies or high-risk HLA-DR and DQ alleles were also similar. Children with a single islet antibody did not differ from those with multiple antibodies.

CONCLUSIONS

The frequency of various islet-antibodies, in isolation and combination, differed considerably from studies among children of European descent with T1DM. Children with T1DM who were islet antibody-negative were indistinguishable from those who were antibody-positive.

Study of the diagnostic efficiency of anti-ZnT8 autoantibodies for type 1 diabetes in pediatric patients

OBJECTIVE

Zinc transporter 8 autoantibodies (ZNt8A) are 1 of the 4 main autoantibodies used for the diagnosis of type 1 diabetes (T1D), with glutamic acid decarboxylase autoantibodies (GADA), islet antigen-2 autoantibodies (IA-2A), and insulin autoantibodies (IAA). The objective of this study is to evaluate the diagnostic efficiency of these autoantibodies for the diagnosis of T1D in pediatric patients.

METHODS

A retrospective analysis of patients under 16 years of age with suspected T1D was made between June 2020 and January 2021. A total of 80 patients were included in the study, with 1 sample per patient. Subjects were classified according to diagnosis.

RESULTS

Of the subjects included in the study, 50 developed T1D. The diagnostic efficacy was IA-2A (cutoff ≥ 28 U/L) sensitivity 0.26 (95% CI: 0.14-0.38) and specificity 0.97 (95% CI: 0.79-1.0); GADA (cutoff ≥ 17 U/mL) sensitivity 0.40 (95% CI: 0.26-0.54) and specificity 0.87 (95% CI: 0.75-0.99); ZnT8A (cut off ≥ 15 U/L) sensitivity 0.62 (95% CI: 0.49-0.75) and specificity 0.97 (95% CI: 0.90-1.0). ZnT8A obtained the most significantly global diagnostic accuracy (0.75), and GADA with ZnT8A showed the highest correlation.

CONCLUSION

The results obtained indicate a higher efficiency of anti-ZnT8 autoantibodies for the diagnosis of T1D in pediatric patients. Clinical efficiency of diabetic autoantibodies is method and assay dependent and influences combined diagnostic strategies.

High Frequency of Recessive WFS1 Mutations Among Indian Children With Islet Antibody-negative Type 1 Diabetes

BACKGROUND

While the frequency of islet antibody-negative (idiopathic) type 1 diabetes mellitus (T1DM) is reported to be increased in Indian children, its aetiology has not been studied. We investigated the role of monogenic diabetes in the causation of islet antibody-negative T1DM.

METHODS

We conducted a multicenter, prospective, observational study of 169 Indian children (age 1-18 years) with recent-onset T1DM. All were tested for antibodies against GAD65, islet antigen-2, and zinc transporter 8 using validated ELISA. Thirty-four islet antibody-negative children underwent targeted next-generation sequencing for 31 genes implicated in monogenic diabetes using the Illumina platform. All mutations were confirmed by Sanger sequencing.

RESULTS

Thirty-five (21%) children were negative for all islet antibodies. Twelve patients (7% of entire cohort, 34% of patients with islet antibody-negative T1DM) were detected to have pathogenic or likely pathogenic genetic variants. The most frequently affected locus was WFS1, with 9 patients (5% of entire cohort, 26% of islet antibody-negative). These included 7 children with homozygous and 1 patient each with a compound heterozygous and heterozygous mutation. Children with Wolfram syndrome 1 (WS) presented with severe insulin-requiring diabetes (including 3 patients with ketoacidosis), but other syndromic manifestations were not detected. In 3 patients, heterozygous mutations in HNF4A, ABCC8, and PTF1A loci were detected.

CONCLUSION

Nearly one-quarter of Indian children with islet antibody-negative T1DM had recessive mutations in the WFS1 gene. These patients did not exhibit other features of WS at the time of diagnosis. Testing for monogenic diabetes, especially WS, should be considered in Indian children with antibody-negative T1DM.

Fourier-transform infrared spectroscopy: a universal optical sensing technique with auspicious application prospects in the diagnosis and management of autoimmune diseases

Autoimmune diseases (AIDs) are poorly understood clinical syndromes due to breakdown of immune tolerance towards specific types of self-antigens. They are generally associated with an inflammatory response mediated by lymphocytes T, autoantibodies or both. Ultimately, chronic inflammation culminates in tissue damages and clinical manifestations. AIDs affect 5% of the world population, and they represent the main cause of fatality in young to middle-aged females. In addition, the chronic nature of AIDs has a devastating impact on the patient's quality of life. It also places a heavy burden on the health care system. Establishing a rapid and accurate diagnosis is considered vital for an ideal medical management of these autoimmune disorders. However, for some AIDs, this task might be challenging. Vibrational spectroscopies, and more particularly Fourier-transform infrared (FTIR) spectroscopy, have emerged as universal analytical techniques with promising applications in the diagnosis of various types of malignancies and metabolic and infectious diseases. The high sensitivity of these optical sensing techniques and their minimal requirements for test reagents qualify them to be ideal analytical techniques. The aim of the current review is to explore the potential applications of FTIR spectroscopy in the diagnosis and management of most common AIDs. It also aims to demonstrate how this technique has contributed to deciphering the biochemical and physiopathological aspects of these chronic inflammatory diseases. The advantages that can be offered by this optical sensing technique over the traditional and gold standard methods used in the diagnosis of these autoimmune disorders have also been extensively discussed.

The relationship between GAD65 autoantibody and the risk of T1DM onset

Objectives

Type 1 diabetes mellitus (T1DM) is a well-known autoimmune disease, characterized by β-cell destruction in pancreas islet cells, which results insulin deficiency and subsequent hyperglycemic sequelae. While there is screening for type 2 DM that leads to better glycemic control and outcome, the majority of T1DM patients are diagnosed when much of the pancreatic cells and their function are disturbed. The aim of this article is to present an overview of the effective factors in the positivity of Glutamic acid decarboxylase antibody )GADA( and identifying the high-risk individuals for T1DM.

Methods

We searched English literature available at National Library of Medicine via PubMed, and Google Scholar through December 2020. Finally, 79 papers have been included in the study. Studies were summarized based on the number of positive autoantibodies and onset of T1DM over time and GADA correlation with different variables.

Conclusions

GADA is an easy marker to measure that can be detected many months prior to the clinical presentation and remains positive even after early childhood.

Ten years follow up of first degree relatives of type 1 diabetes patients: presence of autoimmune biomarkers and the progression to diabetes in a retrospective cohort

OBJECTIVE

The aim of the study was to assess the autoimmunity in first degrees relatives (FDR) of patients with type 1 diabetes (T1DM) and the progression to T1DM after 10 years of follow up in the Brazilian population.

METHODS

Non-diabetic FDR of T1DM patients were interviewed and blood was drawn for autoantibodies measurement (GADA, IA-2A, IAA, ZnT8A). Serum samples were analyzed by standard radioligand binding assays performed at the Federal University of Rio de Janeiro (GADA, IAA and IA2A), and at the Skäne University Hospital, Sweden (ZnT8A). The FDR were interviewed by phone after 10 years to determine if they had developed T1DM. Descriptive statistical analysis was performed and results were described as means and standard deviation (SD).

RESULTS

81 individuals were analyzed. Thirteen subjects had positive autoantibodies associated with T1DM.10 were positive for 1 autoantibody and 3 subjects were positive for multiple autoantibodies (1 of them showed positivity for 2 autoantibodies - GADA, ZnT8A - and the other two were positive for 3 autoantibodies - GADA, IA2A, ZnT8A). The 3 subjects with multiple positive autoantibodies developed T1DM within 10 years.

CONCLUSION

In Brazilian FDR of T1DM patients, the positivity for multiple autoantibodies indicate a greater chance of progression to T1DM, similar to observed in Caucasians. ZnT8A was helpful in the risk assessment for T1DM development.

High prevalence of idiopathic (islet antibody-negative) type 1 diabetes among Indian children and adolescents

OBJECTIVES

To study the prevalence and clinical characteristics of islet antibody-negative (idiopathic) type 1 diabetes mellitus (T1DM) among Indian children and adolescents at the time of diagnosis of illness.

METHODS

In a hospital-based cross-sectional study, we studied 110 patients with T1DM aged ≤18 years. This included 61 patients with duration of diabetes ≤2 weeks (mean ± SD age of onset 9.9 ± 4.4 years) and 49 patients with duration 2 to 12 weeks. Antibodies against GAD65 (GADA), IA-2 (IA-2A) and zinc transporter 8 (ZnT8A), detected by radio-binding assay, were measured in all patients. Insulin autoantibody (IAA) was measured only in subjects with duration ≤2 weeks, using a competitive radio-binding assay.

RESULTS

The prevalence of GADA, IA-2A, and ZnT8A was 53%, 34%, and 29% respectively, while IAA (measured in 61 patients) was detected in 31%. All four antibodies were absent in 17 of 61 (28%) patients. The prevalence of islet antibody-negative patients was similar among both sexes and in children with onset younger and older than 10 years. ZnT8A was the only antibody detected in four patients, and its measurement resulted in 6% reduction in islet antibody-negative patients. Patients with idiopathic T1DM did not differ in their clinical features or fasting plasma C-peptide at the onset and after follow-up of 1 year. Compared with idiopathic T1DM, antibody-positive patients had an increased allele frequency of HLA DRB1*0301 (46% vs 14%, OR = 5.10 [confidence interval = 1.61-16.16], P = .003).

CONCLUSION

Nearly 30% of Indian patients were negative for all islet antibodies at the onset of T1DM. Patients with idiopathic T1DM had similar clinical features to antibody-positive subjects.

Differential HLA Association of GAD65 and IA2 Autoantibodies in North Indian Type 1 Diabetes Patients

The human leucocyte antigen (HLA) association with type 1 diabetes (T1D) is well known but there are limited studies investigating the association between β-cell autoantibodies and HLA genes. We evaluated the prevalence of GAD65 and IA-2 autoantibodies (GADA and IA2A) in 252 T1D patients from North India and investigated the genetic association of GADA and IA2A with HLA class I and class II genes/haplotypes. GADA and IA2A were detected in 50.79% and 15.87% of T1D patients, respectively, while only 8.73% had both GADA and IA2A. HLA-DRB1^∗03 was observed to be significantly higher in GADA+ T1D patients as compared to GADA- (91.41% vs. 66.13%, Bonferroni-corrected P (P _c) = 1.11 × 10^-5; OR = 5.45; 95% CI: 2.67-11.08). Similarly, HLA-DQB1^∗02 was found to be significantly increased in GADA+ patients (94.53%, P _c = 2.19 × 10^-5; OR = 6.27; 95% CI: 2.7-14.49) as compared to GADA- (73.39%). The frequencies of HLA-DRB1^∗04 and DQB1^∗03 were increased in IA2A+ patients (45.0% and 52.5%, respectively) as compared to that in IA2A- (25.94% and 33.96%, respectively). Further, the frequency of DRB1^∗03-DQB1^∗02 haplotype was found to be significantly increased in GADA+ T1D patients as compared to GADA- (60.55% vs. 41.94%, P = 3.94 × 10^-5; OR = 2.13; 95%CI = 1.49-3.03). Similarly, HLA-DRB1^∗04-DQB1^∗03 haplotype was found to be significantly increased in IA2A+ T1D patients compared to IA2A- patients (22.5% vs. 12.97%; P = 0.041; OR = 1.95; 95%CI = 1.08-3.52). None of the HLA class I genes (HLA-A, B, and Cw) was found to be associated with GADA or IA2A in people with T1D. Our findings suggest that HLA-DRB1^∗03/DQB1^∗02 and HLA-DRB1^∗04/DQB1^∗03 might play an important role in the development of GADA and IA2A, respectively.

Identification of a subgroup of black South Africans with type 1 diabetes who are older at diagnosis but have lower levels of glutamic acid decarboxylase and islet antigen 2 autoantibodies

AIMS

To compare the age at diagnosis and prevalence of islet autoantibody [glutamic acid decarboxylase (65 kDa) 65 and islet antigen 2] positivity in black and white participants with type 1 diabetes in South Africa, and to analyse the relationship between age at diagnosis and the presence of autoantibodies.

METHODS

Participants were recruited from diabetes outpatient departments and autoantibodies to glutamic acid decarboxylase (65 kDa) and islet antigen 2 were measured by enzyme-linked immunosorbent assay.

RESULTS

We recruited 472 (353 black and 119 white) participants with type 1 diabetes. Age at diagnosis of diabetes was later in black (19.7 ± 10.5) than in white participants (12.7 ± 10.8 years; P < 0.001) with a median (interquartile range) disease duration of 5.0 (2.0-10.0) and 8.5 (4.0-20.0) years (P < 0.001), respectively. An older age at diagnosis (≥ 21 years) was more frequent in black (152 of 340, 45%) than in white participants (24 of 116, 21%; P < 0.001). The prevalence of islet antigen 2 autoantibodies was 19% (66/352) in black and 41% in white participants (48/118; P < 0.001). There was no significant difference in glutamic acid decarboxylase (65 kDa) autoantibody positivity between black (212/353, 60%) and white participants (77/117, 66%; P = 0.269). In black, but not white, participants the prevalence of both glutamic acid decarboxylase (65 kDa) and islet antigen 2 autoantibody positivity was significantly lower in participants diagnosed at age ≥ 21 years (P < 0.001 for both comparisons).

CONCLUSIONS

The older age at diagnosis, lower prevalence of islet antigen 2 autoantibodies and a distinct subgroup of participants with type 1 diabetes with age at diagnosis of > 20 years in the black compared to white population suggest a difference in the immunological aetiology of type 1 diabetes in these two population groups.

Islet, thyroid and transglutaminase antibodies in adult Bulgarian patients with type 1 diabetes

AIM

The aim of the study was to assess the prevalence and relationship of islet antibodies and autoantibodies of the most common associated autoimmune diseases-autoimmune thyroid disease (AITD) and celiac disease, in adult Bulgarian patients with type 1 diabetes of short duration.

MATERIAL AND METHODS

160 type 1 diabetes patients, of mean age 36.3 ± 10.9 years, mean BMI 23.0 ± 4.2 kg/m² and mean disease duration 1.35 ± 1.69 years were enrolled. Pancreatic islet cell antibodies-glutamic acid decarboxylase antibodies (GAD 65-Ab), tyrosine phosphatase antibodies (IA 2-Ab), and zinc transporter 8 antibodies (ZnT8-Ab), thyroid antibodies-thyroperoxidase and thyroglobulin antibodies, and transglutaminase antibodies (TTG-IgA-Ab) were assessed by ELISA.

RESULTS

87.5% of the patients had one or more of the islet antibodies-78.1% had GAD 65-Ab, 53.1%-ZnT8-Ab, and 34.4%-IA 2-Ab. 5% presented as just ZnT8-Ab positive. GAD 65-Ab identified 90.6% of the antibody positive patients. The addition of IA 2-Ab as a second immunologic marker identified 94.4%, while the use of ZnT8-Ab in second place identified 98.8% of the cases. 24.4% presented with positive thyroid antibodies and 33.8% had AITD. No relation was found between any of the islet antibodies and AITD. None of the patients was TTG-IgA-Ab positive. No significant correlations were established between the antibodies with different organ specificity.

CONCLUSIONS

In adult Bulgarian type 1 diabetes patients ZnT8-Ab is an independent diagnostic marker rating second in prevalence and diagnostic significance after GAD 65-Ab. AITD affects about one third of this population and routine screening is required, while screening for celiac disease is not justified.

Profile of Auto-antibodies (Disease Related and Other) in Children with Type 1 Diabetes

BACKGROUND

Type 1 diabetes is associated with several disease-related and other organ-specific autoimmune disorders. Data related to various auto-antibodies in Type 1 diabetes in India is limited.

MATERIALS AND METHODS

In this cross sectional study, 92 subjects with T1DM (33 males, 59 females) were evaluated for T1DM related antibodies (autoantibodies to glutamic acid decarboxylase (anti-GAD), autoantibodies to protein tyrosine phosphatise (anti-IA2), anti-islet cell antibody (ICA), insulin autoantibody (IAA), anti-Zinc Transporter(ZnT8) and other organ specific auto antibodies like anti-thyroid peroxidase (anti-TPO), anti-thyroglobulin (TgAb), IgA anti-tissue transglutaminase (IgA anti-tTG), anti-21-hydroxylase, and anti-ovarian antibody (in females).

RESULTS

Anti-GAD, IA-2, islet cell antibody, insulin autoantibodies (IAA), ZnT8 antibody were present in 79.3%, 32.6%, 61.9%, 63%, and 20.65% subjects, respectively. Only 2.2% patients with Type 1 diabetes were antibody negative. At least one antibody was found in 97.8% and at least two antibodies in 67.3%. The presence of anti-TPO, anti-thyroglobulin, IgA anti-tissue transglutaminase, anti 21-hydroxylase were found in 51%, 25%, 22.8%, and 2.1%, respectively. Anti-ovarian antibody was absent in all females of our study population. The duration of diabetes positively correlated with the number of T1DM specific antibody and also with GAD antibody positivity. Anti TPO positivity correlated with the age of onset of T1DM, but not with the duration of disease or presence of other T1DM specific autoantibody.

CONCLUSIONS

T1DM is associated with a high prevalence of autoantibodies and antibody negative T1DM is rare. The association with other organ specific antibody (especially thyroid and adrenal glands) and celiac disease is also substantial, which reinforces the importance of regular thyroid and celiac disease screening in T1DM subjects. The duration of diabetes positively correlated with number of T1DM specific antibodies.

Clinical features, biochemistry and HLA-DRB1 status in children and adolescents with diabetes in Dhaka, Bangladesh

AIMS

Little information is published on diabetes in young people in Bangladesh. We aimed to investigate the demographic, clinical, and biochemical features, and HLA-DRB1 alleles in new cases of diabetes affecting Bangladeshi children and adolescents <22 years of age.

METHODS

The study was conducted at Bangladesh Institute of Research and Rehabilitation of Diabetes, Endocrine and Metabolic Disorders (BIRDEM) in Dhaka. One hundred subjects aged <22 years at diagnosis were enrolled. Demographic characteristics, clinical information, biochemical parameters (blood glucose, HbA1c, C-peptide, and autoantibodies against glutamic acid decarboxylase 65 (GADA) and islet antigen-2 (IA-2A) were measured. High-resolution DNA genotyping was performed for HLA-DRB1.

RESULTS

Eighty-four subjects were clinically diagnosed as type 1 diabetes (T1D), seven as type 2 diabetes (T2D), and nine as fibrocalculous pancreatic disease (FCPD). Of the 84 with T1D, 37 (44%) were males and 47 (56%) females, with median age at diagnosis 13 years (y) (range 1.6-21.7) and peak age at onset 12-15 years. 85% of subjects were assessed within one month of diagnosis and all within eleven months. For subjects diagnosed with T1D, mean C-peptide was 0.46 ± 0.22 nmol/L (1.40 ± 0.59 ng/mL), with 9 (10.7%) IA-2A positive, 22 (26%) GADA positive, and 5 (6%) positive for both autoantibodies. Analysis of HLA-DRB1 genotypes revealed locus-level T1D association (p = 6.0E-05); DRB1*04:01 appeared predisposing (p < 3.0E-06), and DRB1*14:01 appeared protective (p = 1.7E-02).

CONCLUSIONS

Atypical forms of T1D appear to be more common in young people in Bangladesh than in European populations. This will be helpful in guiding more specific assessment at onset and potentially, expanding treatment options.

Clinical features, biochemistry and HLA-DRB1 status in youth-onset type 1 diabetes in Pakistan

Published information on diabetes in Pakistani youth is limited. We aimed to investigate the demographic, clinical, and biochemical features, and HLA-DRB1 alleles in new cases of diabetes affecting children and adolescents <22 years of age. The study was conducted at Baqai Institute of Diabetology and Endocrinology in Karachi from June 2013-December 2015. One hundred subjects aged <22 years at diagnosis were enrolled. Demographic characteristics, clinical information, biochemical parameters (blood glucose, HbA1c, C-peptide, glutamic acid decarboxylase 65 (GAD65) and islet antigen 2 (IA-2) autoantibodies) were measured. DNA from 100 subjects and 200 controls was extracted and genotyped for HLA-DRB1 using high-resolution genotyping technology. Ninety-nine subjects were clinically diagnosed as type 1 diabetes (T1D) and one as type 2 diabetes (T2D). Of the 99 with T1D, 57 (57.6%) were males and 42 (42.4%) females, with mean age at diagnosis 11.0 ± 5.2 years (range 1.6-21.7 years) and peaks at six and fifteen years. Fifty-seven subjects were assessed within one month of diagnosis and all within eleven months. For the subjects diagnosed as T1D, mean C-peptide was 0.63 ± 0.51 nmol/L (1.91 ± 1.53 ng/mL), with 16 (16.2%) IA2 positive, 53 (53.5%) GAD-65 positive, and 10 (10.1%) positive for both autoantibodies. In T1D patients, the allele DRB1*03:01 demonstrated highly significant T1D association (p < 10-16), with no apparent risk conferred by DRB1*04:xx alleles. CONCLUSIONS: Heterogeneous forms of T1D appear more common in children and youth in Pakistan than in European populations. Individual understanding of such cases could enable improved management strategies and healthier outcomes.

A Systematic Review of Childhood Diabetes Research in the Middle East Region

Background: Diabetes mellitus (DM) is a common chronic disorder in children and is caused by absolute or relative insulin deficiency, with or without insulin resistance. There are several different forms of childhood DM. Children can suffer from neonatal diabetes mellitus (NDM), type 1 diabetes (T1DM), type 2 diabetes (T2DM), Maturity Onset Diabetes of the Young (MODY), autoimmune monogenic, mitochondrial, syndromic and as yet unclassified forms of DM. The Middle East has one of the highest incidences of several types of DM in children; however, it is unclear whether pediatric diabetes is an active area of research in the Middle East and if ongoing, which research areas are of priority for DM in children. Objectives: To review the literature on childhood DM related to research in the Middle East, summarize results, identify opportunities for research and make observations and recommendations for collaborative studies in pediatric DM. Methods: We conducted a thorough and systematic literature review by adhering to a list recommended by PRISMA. We retrieved original papers written in English that focus on childhood DM research, using electronic bibliographic databases containing publications from the year 2000 until October 2018. For our final assessment, we retrieved 429 full-text articles and selected 95 articles, based on our inclusion and exclusion criteria. Results: Our literature review suggests that childhood DM research undertaken in the Middle East has focused mainly on reporting retrospective review of case notes, a few prospective case studies, systemic reviews, questionnaire-based studies, and case reports. These reported studies have focused mostly on the incidence/prevalence of different types of DM in childhood. No studies report on the establishment of National Childhood Diabetes Registries. There is a lack of consolidated studies focusing on national epidemiology data of different types of childhood DM (such as NDM, T1DM, T2DM, MODY, and syndromic forms) and no studies reporting on clinical trials in children with DM. Conclusions: Investing in and funding basic and translational childhood diabetes research and encouraging collaborative studies, will bring enormous benefits financially, economically, and socially for the whole of the Middle East region.

Prevalence of islet autoantibodies in Thai juvenile-onset type 1 diabetes

BACKGROUND

Type 1 diabetes mellitus (T1DM) is caused by autoimmune destruction of islet β-cells of the pancreas. There are overlapping phenotypes in a significant proportion of youth with type 1 and 2 diabetes. Thus, positive pancreatic autoantibodies are helpful to diagnose T1DM. Zinc transporter 8 antibody (ZnT8A) is a recently identified autoantibody in T1DM and no data on ZnT8A in the Thai population have been reported. The aim of this study was therefore to estimate the prevalence of ZnT8A in Thai juvenile-onset T1DM and to evaluate its diagnostic value relative to glutamic acid decarboxylase and insulinoma-2 antigen antibodies (GADA and IA2A).

METHODS

In this cross-sectional study, patients with T1DM diagnosed before age 15 years, and disease duration <10 years were enrolled. Serum ZnT8A, GADA, and IA2A were measured using commercial enzyme-linked immunosorbent assay kits.

RESULTS

The subjects consisted of 81 youths (30 boys, 51 girls) aged 12.3 ± 4.5 years with T1DM. The median diabetes duration was 3 years (range, 0-10 years). The prevalence of ZnT8A, GADA, and IA2A was 54.3%, 75.3%, and 45.7%, respectively. ZnT8A were detected in 16% of T1DM patients negative for both GADA and IA2A. A combination of ZnT8A, GADA and IA2A could detect 80.2% of patients with T1DM. Combined use of ZnT8A and GADA identified 100% of antibody-positive patients.

CONCLUSION

The prevalence of ZnT8A in Thai juvenile-onset T1DM appears to be higher than in previous studies from Asia. ZnT8A could replace IA2A as an autoimmunity marker in Thai pediatric T1DM patients, with better diagnostic performance.

Could ZnT8 antibodies replace ICA, GAD, IA2 and insulin antibodies in the diagnosis of type 1 diabetes?

BACKGROUND

The zinc transporter 8 (ZnT8) is an islet β-cell secretory granule membrane protein coded by the SLC30A8 gene, identified as a novel autoantigen in human type 1 diabetes (T1D). As no data of ZnT8ab in Algerian patients have been reported, we aim to evaluate the prevalence of ZnT8ab in young Algerians with T1D and determine whether ZnT8ab could be a better diagnostic tool to replace the other conventional autoantibodies detected in patients with type 1 diabetes. For this purpose, we evaluated the prevalence of islets cells antibodies (ICA), glutamic acid decarboxylase (GAD), islet antigen type 2 (IA2), insulin (IA) autoantibodies (ab) and for the first time in Algeria, the zinc transporter 8 (ZnT8) in young Algerian patients with type 1 diabetes.

PATIENTS AND METHODS

In our cross-sectional study, 160 patients between 1 and 35 years old, diagnosed with type 1 diabetes were enrolled. ICAab was analyzed by indirect immunofluorescence (IIF), GADab, IA2ab, IAab and ZnT8ab were analyzed by ELISA, fasting blood glucose was performed by enzymatic method (glucose-oxidase) and HbA1c by turbid metric method.

RESULTS

Our cohort was composed with 74 males and 86 females (OR=1.16); the mean of age was 14.09 [1-35] years old and the median diabetes duration was 4.10 [1-18] years. Our cohort had a mean of HbA1c of 9.22 [5.40-15]%, the mean of birth weight was 3360.52 [2200-4800]g; the mean of BMI was 19.30 [16.04-22.46]kg/m². Out of 160 patients, 44 (27.5%) were under mother breastfeeding and 116/160 (72.5%) were under artificial feeding. One antibody, at least, was found in 94.38% and the ZnT8ab was significantly more positive in females (70.3%) than in males (10.7%) (***P=8.033×10^-15). The concentration of ZnT8ab was higher in females than in males (females=122.25UI/mL versus males=51.38UI/mL; *P=0.03); ICAab, GADab and ZnT8ab were more present in patients with consanguineous parents (***P=0.0002, *P=0.019 and *P=0.03; respectively) CONCLUSION: Our study on ZnT8ab in T1D is the first in the Maghreb region and we observed a prevalence of 46.25%. The positivity of ZnT8ab enabled us to classify in T1DA 50% of diabetics with obvious T1D phenotype and negative routine autoantibodies, thus ZnT8ab is a good tool for differential diagnosis of type 1 diabetes. According to our results, a simultaneous analysis for ZnT8 and IA2 autoantibodies can be a better and efficient diagnosis of type 1A diabetes from the beginning of the disease.

Screening of ZnT8 autoantibodies in the diagnosis of autoimmune diabetes in a large French cohort

AIM OF THE STUDY

Evaluate the added value of screening anti-ZnT8 antibodies (ZnT8A) in addition to the classical anti-GAD (GADA) and anti-IA-2 (IA-2A) antibodies for the diagnosis of type-1 diabetes (T1D) within a large cohort of both children and adults.

MATERIALS AND METHODS

Retrospective 2-year study including 516 patients (215 children, 301 adults) who had blood tests at diabetes onset and/or for diabetes classification. ZnT8A, GADA, and IA-2A were analyzed in all samples.

RESULTS

Among those individuals included, 142 (28%) were ZnT8A-positive. A total of 228/516 suffered from T1D, of whom 110 (48%) were ZnT8A-positive and 166 (73%) GADA and/or IA-2A positive. When adding ZnT8A to GADA/IA-2A, 184 (81%) patients were positive for ≥1 Ab. Regarding the 122 patients at T1D onset, 75 (61%) were positive for ZnT8A and the proportion of patients with T1D with ≥1 Ab reached 89%. The highest prevalence of ZnT8A was observed in children aged 6-10years. Fourteen of the 124 patients positive for ZnT8A with a known clinical diagnosis suffered from a disease other than T1D.

CONCLUSIONS

ZnT8A should be included in routine evaluation at diabetes onset and is a valuable biological marker to classify newly-diagnosed diabetics. The predictive value in our high-risk subjects has to be confirmed.

Zinc transporter 8 autoantibodies assessment in daily practice

OBJECTIVES

Zinc transporter 8 (ZnT8) is specifically expressed in the pancreatic β-cell and is more restricted in its tissue distribution than other auto-antigens as glutamic acid decarboxylase 65 (GAD₆₅) and insulinoma-associated antigen-2 (IA2). ZnT8 autoantibodies (ZnT8A) assessment allows identifying rapid progression to clinical onset of the disease. We evaluated the prevalence of ZnT8A in adults of different ethnic and phenotypic groups and analyzed its potential utility as additional marker of autoimmunity in daily practice.

METHODS

ZnT8A, GADA and IA2A were assessed using enzyme-linked immune-sorbent assay (ELISA) in 160 controls and 216 diabetic subjects. 105 were of type 1 diabetes (T1D), 17 had Latent Autoimmune Diabetes of Adults (LADA), 38 were type 2 diabetic (T2D) and 56 had ketosis-prone diabetes (KPD). 82 patients were newly diagnosed cases.

RESULTS

ZnT8A were detected in 1% of controls and were not found in any of our 38 T2D subjects or 56 KPD subjects. In contrast, ZnT8A were detected in 18% of LADA subjects and in 38% of T1D subjects. A slight difference of percentage of ZnT8A positivity was found among our T1D ethnic groups. ZnT8A were positive in 41% of patients positive for GADA and 67% of patients positive for IA2A. The percentage of stratification achieved 91% when GADA, IA2A and ZnT8A were assessed simultaneously.

CONCLUSIONS

Results obtained for ZnT8A measurement using ELISA were consistent with previous data. Such investigation could improve the risk stratification and would be integrated in our daily practice.

Organ-specific autoimmunity in relation to clinical characteristics in children with long-lasting type 1 diabetes

BACKGROUND

The aim of this study was to assess the prevalence of diabetes and other organ-specific autoantibodies (Ab) associated with various autoimmune conditions, in Polish children with type 1 diabetes mellitus (T1DM).

METHODS

In this study 114 patients, aged 13.4 years, with mean diabetes duration 5.2 years were included. Ab to islet cell antigens: glutamic acid decarboxylase (GAD), insulinoma antigen 2 (IA-2), zinc transporter 8 (ZnT8), together with thyroid peroxidase Ab (TPO Ab), thyroglobulin Ab (Tg Ab), tissue transglutaminase Ab (tTG Ab) and 21-hydroxylase Ab (21-OH Ab) were measured.

RESULTS

The prevalence of at least one diabetes associated Ab was found in 87%, with the highest prevalence of 64% for ZnT8 Ab. In patients with disease duration <5 years, at least one antibody was present in 90%, the most prevalent was ZnT8 Ab (72%). In patients with duration >10 years, 50% had at least one antibody. The prevalence of other than islet cell autoimmunity was high (34%). Thyroid Ab were detected in 26% patients, 42% in girls vs. 8% in boys, p<0.001. tTG Ab were found in 11% patients, with a greater prevalence in children with early onset (p=0.01). 21-OH Ab were found in 2.6% T1DM patients.

CONCLUSIONS

Islet Ab were found in most T1DM children and remained positive even 10 years after onset. ZnT8 Ab emerged as an important marker for the diagnosis of T1DM in the Polish children. Screening for non-diabetes Ab in T1DM may be helpful in identifying subclinical cases of autoimmune thyroid, celiac or Addison's disease (AD).

Anti-zinc transporter protein 8 autoantibodies significantly improve the diagnostic approach to type 1 diabetes: an Italian multicentre study on paediatric patients

BACKGROUND AND AIM

Anti-ZnT8 antibodies (ZnT8A) were recently proposed as a new independent serological marker in Type 1 diabetes (T1D), leading to a significant improvement of the positive predictive value of autoantibody measurement in this setting. The aim of this retrospective multicentre study was to investigate ZnT8A as a complement to the current T1D autoantibody assays in a large cohort of paediatric Italian patients.

METHODS

ZnT8A were assessed by ELISA in 213 T1DM paediatric patients referred to six different centres in North-East Italy. Fifty-four were analysed at disease onset, 79 within 4 years from diagnosis and 80 after 5 or more years from diagnosis. Retrospective data about islet cell autoantibodies (ICA), anti-insulin (IAA), anti-glutamate decarboxylase (GADA) and anti-protein tyrosine phosphatase IA-2 (IA-2A) antibodies were collected and compared.

RESULTS

Overall, ZnT8A showed positive results in 106/213 (49.8 %) T1D patients and were found in 10 (4.7 %) subjects previously classified as autoantibody negative based on the existing markers (GADA, IA-2A, IAA and ICA), increasing the overall diagnostic sensitivity from 85.9 to 90.6 %. ZnT8A disclosed the same sensitivity (61.1 %) at disease onset as GADA (61.1 %) and higher than IA-2A (53.7 %), with only GADA showing much persistence in the long-term follow-up. Focusing on patients at disease onset, all the ICA positive were associated with at least one positive autoantibody among GADA, IA-2A and ZnT8A, 16.7 % of whom presenting only anti-ZnT8-positive antibodies.

CONCLUSION

This study confirms ZnT8A as an important additional and independent diagnostic marker of T1D and supports its introduction in the routine diagnostic process to replace less sensitive methods and improve the overall autoantibody sensitivity.