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- Hampe, C. S., et al.
(författare)
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Reduced display of conformational epitopes in the N-terminal truncated GAD65 isoform : relevance for people with stiff person syndrome or DQ8/8-positive Type 1 diabetes mellitus
- 2019
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Ingår i: Diabetic Medicine. - : Wiley-Blackwell. - 0742-3071 .- 1464-5491. ; 36:11, s. 1375-1383
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Tidskriftsartikel (refereegranskat)abstract
- Aims: To investigate whether the N‐terminal truncated glutamic acid decarboxylase 65 (GAD65) isoform is as well recognized by people with stiff person syndrome as it is by people with Type 1 diabetes, and whether conformational GAD65 antibody epitopes are displayed properly by the isoform.Methods: GAD65 antibody‐positive healthy individuals (n=13), people with stiff‐person syndrome (n=15) and children with new‐onset Type 1 diabetes (n=654) were analysed to determine binding to full‐length GAD65 and the N‐terminal truncated GAD65 isoform in each of these settings. GAD65 autoantibody epitope specificity was correlated with binding ratios of full‐length GAD65/N‐terminal truncated GAD65.Results: The N‐terminal truncated GAD65 isoform was significantly less recognized in GAD65Ab‐positive people with stiff‐person syndrome (P=0.002) and in healthy individuals (P=0.0001) than in people with Type 1 diabetes. Moreover, at least two specific conformational GAD65Ab epitopes were not, or were only partially, presented by the N‐terminal truncated GAD65 isoform compared to full‐length GAD65. Finally, an N‐terminal conformational GAD65Ab epitope was significantly less recognized in DQ8/8 positive individuals with Type 1 diabetes (P=0.02).Conclusions: In people with stiff person syndrome preferred binding to the full‐length GAD65 isoform over the N‐terminal truncated molecule was observed. This binding characteristic is probably attributable to reduced presentation of two conformational epitopes by the N‐terminal truncated molecule. These findings support the notion of disease‐specific GAD65Ab epitope specificities and emphasize the need to evaluate the applicability of novel assays for different medical conditions.
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| 2. |
- Kanatsuna, N, et al.
(författare)
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Doubly reactive INS-IGF2 autoantibodies in children with newly diagnosed autoimmune (type 1) diabetes
- 2015
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Ingår i: Scandinavian Journal of Immunology. - : Wiley-Blackwell. - 0300-9475 .- 1365-3083. ; 82:4, s. 361-369
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Tidskriftsartikel (refereegranskat)abstract
- The splice variant INS-IGF2 entails the preproinsulin signal peptide, the insulin B-chain, eight amino acids of the C-peptide and 138 unique amino acids from an ORF in the IGF2 gene. The aim of this study was to determine whether levels of specific INS-IGF2 autoantibodies (INS-IGF2A) were related to age at diagnosis, islet autoantibodies, HLA-DQ or both, in patients and controls with newly diagnosed type 1 diabetes. Patients (n = 676), 0-18 years of age, diagnosed with type 1 diabetes in 1996-2005 and controls (n = 363) were analysed for specific INS-IGF2A after displacement with both cold insulin and INS-IGF2 to correct for non-specific binding and identify double reactive sera. GADA, IA-2A, IAA, ICA, ZnT8RA, ZnT8WA, ZnT8QA and HLA-DQ genotypes were also determined. The median level of specific INS-IGF2A was higher in patients than in controls (P < 0.001). Irrespective of age at diagnosis, 19% (126/676) of the patients had INS-IGF2A when the cut-off was the 95th percentile of the controls (P < 0.001). The risk of INS-IGF2A was increased among HLA-DQ2/8 (OR = 1.509; 95th CI 1.011, 2.252; P = 0.045) but not in 2/2, 2/X, 8/8, 8/X or X/X (X is neither 2 nor 8) patients. The association with HLA-DQ2/8 suggests that this autoantigen may be presented on HLA-DQ trans-heterodimers, rather than cis-heterodimers. Autoantibodies reactive with both insulin and INS-IGF2A at diagnosis support the notion that INS-IGF2 autoimmunity contributes to type 1 diabetes.
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| 3. |
- Andersson, C, et al.
(författare)
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The three ZNT8 autoantibody variants together improve the diagnostic sensitivity of childhood and adolescent type 1 diabetes
- 2011
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Ingår i: Autoimmunity. - : Taylor & Francis. - 0891-6934 .- 1607-842X. ; 44:5, s. 394-405
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Tidskriftsartikel (refereegranskat)abstract
- Aims: We tested whether autoantibodies to all three ZnT8RWQ variants, GAD65, insulinoma-associated protein 2 (IA-2), insulin and autoantibodies to islet cell cytoplasm (ICA) in combination with human leukocyte antigen (HLA) would improve the diagnostic sensitivity of childhood type 1 diabetes by detecting the children who otherwise would have been autoantibody-negative.Methods: A total of 686 patients diagnosed in 1996–2005 in Skåne were analyzed for all the seven autoantibodies [arginin 325 zinc transporter 8 autoantibody (ZnT8RA), tryptophan 325 zinc transporter 8 autoantibody (ZnT8WA), glutamine 325 Zinc transporter 8 autoantibody (ZnT8QA), autoantibodies to glutamic acid decarboxylase (GADA), Autoantibodies to islet-antigen-2 (IA-2A), insulin autoantibodies (IAA) and ICA] in addition to HLA-DQ genotypes.Results: Zinc transporter 8 autoantibody to either one or all three amino acid variants at position 325 (ZnT8RWQA) was found in 65% (449/686) of the patients. The frequency was independent of age at diagnosis. The ZnT8RWQA reduced the frequency of autoantibody-negative patients from 7.5 to 5.4%—a reduction by 28%. Only 2 of 108 (2%) patients who are below 5 years of age had no autoantibody at diagnosis. Diagnosis without any islet autoantibody increased with increasing age at onset. DQA1-B1*X-0604 was associated with both ZnT8RA (p = 0.002) and ZnT8WA (p = 0.01) but not with ZnT8QA (p = 0.07). Kappa agreement analysis showed moderate (>0.40) to fair (>0.20) agreement between pairs of autoantibodies for all combinations of GADA, IA-2A, ZnT8RWQA and ICA but only slight ( < 0.19) agreement for any combination with IAA.Conclusions: This study revealed that (1) the ZnT8RWQA was common, independent of age; (2) multiple autoantibodies were common among the young; (3) DQA1-B1*X-0604 increased the risk for ZnT8RA and ZnT8WA; (4) agreement between autoantibody pairs was common for all combinations except IAA. These results suggest that ZnT8RWQA is a necessary complement to the classification and prediction of childhood type 1 diabetes as well as to randomize the subjects in the prevention and intervention of clinical trials.
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