ZnT8A

ZnT8A refers to autoantibodies directed against zinc transporter 8 (ZnT8), a protein expressed in pancreatic beta cells that transports zinc into insulin secretory granules and contributes to insulin maturation. The ZnT8 protein is encoded by the SLC30A8 gene. ZnT8A represents an autoimmune response targeting this beta-cell antigen and is detected in a substantial subset of individuals with autoimmune diabetes.

ZnT8A is used as part of islet autoantibody profiling to support the diagnosis of type 1 diabetes and to assess disease risk in at‑risk individuals. It is commonly measured alongside other major islet autoantibodies, including GAD65 (GADA), IA-2 (IA-2A), and insulin autoantibodies (IAA). The presence of ZnT8A, especially in combination with other autoantibodies, supports an autoimmune etiology of hyperglycemia and can aid in distinguishing type 1 diabetes from other forms of diabetes.

Prevalence and testing: In children with new-onset type 1 diabetes, ZnT8A is detected in roughly 60–80% of cases, with somewhat lower frequencies observed in adults. Specificity for autoimmune diabetes is high. Assay methods include enzyme‑linked immunosorbent assays (ELISA) and radiobinding assays, and some tests incorporate ZnT8 variants (such as different amino acid at position 325) to capture a broader antibody repertoire.

Interpretation and limitations: A positive ZnT8A test supports β-cell autoimmunity but is not the sole determinant of diagnosis. A negative result does not exclude type 1 diabetes or autoimmunity, nor does it by itself rule out a need for monitoring. ZnT8A status is most informative when considered with clinical presentation and other autoantibody results.