| 1. |
- Andersen, Marie Louise M., et al.
(författare)
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Association between autoantibodies to the Arginine variant of the Zinc transporter 8 (ZnT8) and stimulated C-peptide levels in Danish children and adolescents with newly diagnosed type 1 diabetes
- 2012
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Ingår i: Pediatric Diabetes. - : Hindawi Limited. - 1399-543X .- 1399-5448. ; 13:6, s. 454-462
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Tidskriftsartikel (refereegranskat)abstract
- Background The zinc transporter 8 (ZnT8) was recently identified as a common autoantigen in type 1 diabetes (T1D) and inclusion of ZnT8 autoantibodies (ZnT8Ab) was found to increase the diagnostic specificity of T1D. Objectives The main aims were to determine whether ZnT8Ab vary during follow-up 1 year after diagnosis, and to relate the reactivity of three types of ZnT8Ab to the residual stimulated C-peptide levels during the first year after diagnosis. Subjects A total of 129 newly diagnosed T1D patients <15 years was followed prospectively 1, 3, 6, and 12 months after diagnosis. Methods Hemoglobin A1c, meal-stimulated C-peptide, ZnT8Ab, and other pancreatic autoantibodies were measured at each visit. Patients were genotyped for the rs13266634 variant at the SLC30A8 gene and HLA-DQ alleles. Results The levels of all ZnT8Ab [ZnT8Arg (arginine), ZnT8Trp (tryptophan), ZnT8Gln (glutamine)] tended to decrease during disease progression. A twofold higher level of ZnT8Arg and ZnT8Gln was associated with 4.6%/5.2% (p = 0.02), 5.3%/8.2% (p = 0.02) and 8.9%/9.7% (p = 0.004) higher concentrations of stimulated C-peptide 3, 6, and 12 months after diagnosis. The TT genotype carriers of the SLC30A8 gene had 45.8% (p = 0.01) and 60.1% (p = 0.002) lower stimulated C-peptide 6 and 12 months after diagnosis compared to the CC and the CT genotype carriers in a recessive model. Conclusions The levels of the Arg variant of the ZnT8 autoantibodies are associated with higher levels of stimulated C-peptide after diagnosis of T1D and during follow-up. Carriers of the TT genotype of the SLC30A8 gene predict lower stimulated C-peptide levels 12 months after diagnosis.
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| 2. |
- Delli, Ahmed
(författare)
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Immunogenetics of Childhood Type 1 Diabetes in Immigrant Patients in Sweden. Migration Studies on Type 1 Diabetes
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis examined whether the offspring of immigrants (non-Swedes) to Sweden are at increased risk of Type 1 Diabetes (T1D) when they are born or live in Sweden. It also evaluated if their T1D and T2D-related genes differed from Swedish patients and whether this genetic heritage determined the types and existence of islet autoantibodies at time of diagnosis and affected the classification of diabetes. A total of 3451 (55% males) newly diagnosed T1D patients (<18 y) were recruited from the Better Diabetes Diagnosis (BDD) study. We calculated the “patients/105/y” rate of confirmed T1D, which was 14 (95%CI: 13-15) among non-Swedes (8% of total) compared to 22 (95% CI: 21-23) for Swedes (66%). The rate for non-Swedes was at least 2 times higher than the mean incidence rates for countries of parents’ origins. Non-Swedes had predominately GAD65A (64%) in association with DQ2, which prevailed in the non-Swedes (34%, OR=1.5) compared to Swedes (15%). The Swedes had more multiple (>=2) autoantibodies and IA-2A in association with the dominant DQ8 and 2/8. The ZnT8-WA (38%) found less in non-Swedes compared to Swedes (50%), consistent with lower frequency in the non-Swedes (37%) of the SLC30A8 CT+TT than in Swedes (54%). The ZnT8-RA (57% and 58%, respectively) did not differ despite a higher frequency of CC (RR) genotypes in non-Swedes (63%) compared to Swedes (46%). In non-Swedes only, the prevailing DQ2/X (40%) compared to Swedes (14%) was negatively associated with ZnT8-WA (p=0.008) and ZnT8-QA (p=0.03) but not ZnT8-RA (p=0.26). Molecular simulation showed non-binding of the relevant ZnT8R peptide to DQ2 explaining in part the possible lack of tolerance to ZnT8-R by DQ2. The DQ8 and DQ6.4 had stronger binding epitopes outside the polymorphic site at amino acid position 325. The INS-SNP rs689 A/A genotype contributed T1D risk in non-Swedes (65%), though less than Swedes (72%). IAA were predicted by A/A (OR=3.5) but negatively associated with increasing age at diagnosis (OR=0.1) and HLA-DQ2 regardless of ethnic background (OR=0.6) explaining, in addition to INS T/T, the lower IAA in non-Swedes. In the Swedes only, IAA were associated with DQ2/8 (40%) and 8/x (32%), which were also stronger predictors of IAA at a younger age than INS genotypes. Non-Swedes were further subdivided into non-Europeans (n=148, 63%) and European-descent (n=86, 37%). Non-European had less T1D risk genes (HLA DQ and PTPN22) and more T2D risk genes (SLC30A8 and FTO genes), therefore they were more prone to be autoantibody-negative (11% compared to 8% in Europeans and 6% in Swedes)and had less multiple autoantibodies (64%% compared to 81% in Europeans and 79% in Swedes). Our data suggest that immigrants from low incidence countries (80% were born in Sweden), especially non-Europeans, are exposed to higher T1D in Sweden, because their genetic heritage affected by the Swedish environment. Non-European immigrants develop T1D in Sweden with lesser T1D-related genes but more T2D-related genes and less islet autoantibodies when compared to Europeans and native Swedes.
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| 3. |
- Delli, Ahmed, et al.
(författare)
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Zinc Transporter 8 Autoantibodies and Their Association With SLC30A8 and HLA-DQ Genes Differ Between Immigrant and Swedish Patients With Newly Diagnosed Type 1 Diabetes in the Better Diabetes Diagnosis Study
- 2012
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Ingår i: Diabetes. - : American Diabetes Association. - 0012-1797 .- 1939-327X. ; 61:10, s. 2556-2564
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Tidskriftsartikel (refereegranskat)abstract
- We examined whether zinc transporter 8 autoantibodies (ZnT8A; arginine ZnT8-RA, tryptophan ZnT8-WA, and glutamine ZnT8-QA variants) differed between immigrant and Swedish patients due to different polymorphisms of SLC30A8, HLA-DQ, or both. Newly diagnosed autoimmune (andgt;= 1 islet autoantibody) type 1 diabetic patients (n = 2,964, andlt;18 years, 55% male) were ascertained in the Better Diabetes Diagnosis study. Two subgroups were identified: Swedes (n = 2,160, 73%) and immigrants (non-Swedes; n = 212, 7%). Non-Swedes had less frequent ZnT8-WA (38%) than Swedes (50%), consistent with a lower frequency in the non-Swedes (37%) of SLC30A8 CT+TT (RW+WW) genotypes than in the Swedes (54%). ZnT8-RA (57 and 58%, respectively) did not differ despite a higher frequency of CC (RR) genotypes in non-Swedes (63%) than Swedes (46%). We tested whether this inconsistency was due to HLA-DQ as 2/X (2/2; 2/y; y is anything but 2 or 8), which was a major genotype in non-Swedes (40%) compared with Swedes (14%). In the non-Swedes only, 2/X (2/2; 2/y) was negatively associated with ZnT8-WA and ZnT8-QA but not ZnT8-RA. Molecular simulation showed nonbinding of the relevant ZnT8-R peptide to DQ2, explaining in part a possible lack of tolerance to ZnT8-R. At diagnosis in non-Swedes, the presence of ZnT8-RA rather than ZnT8-WA was likely due to effects of HLA-DQ2 and the SLC30A8 CC (RR) genotypes.
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