Zinc transporter 8 autoantibodies assessment in daily practice

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.

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.

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.

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.