The measurement of zinc transporter 8 (ZnT8) antibodies is used in the distinction of type 1 from type 2 diabetes mellitus, in the identification of individuals at risk of type 1 diabetes (including relatives of patients with diabetes, and those with gestational diabetes), and in the prediction of future need for insulin treatment in adult-onset diabetic patients
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Type 1 diabetes, also known as insulin-dependent diabetes mellitus (IDDM), results from chronic autoimmune destruction of the insulin-secreting pancreatic beta cells, probably initiated by exposure of the genetically susceptible host to environmental agents. Autoimmune destruction of beta cells is thought to be completely asymptomatic until 80 – 90% of the cells are lost. This process may take years to complete and may occur at any time in all ages.
During the preclinical phase, this autoimmune process is marked by circulating autoantibodies to beta-cell antigens. These autoantibodies, such as anti-insulin (IAA), anti-glutamic acid decarboxylase (GAD), anti-tyrosine phosphatase (IA2), and zinc transporter 8 (ZnT8), are present years before the onset of type 1 diabetes and prior to clinical symptoms.
Zinc transporter 8 (ZNT8) is a protein that in humans is encoded by the SLC30A8 gene and is related to insulin secretion.
ZnT8 autoantibodies are directed principally to the C terminal domain of ZnT8 (residues 268 – 369). Human population gene polymorphism at the codon for the 325th amino acid results in the expression of three protein variants: Arginine (R) 325, Tryptophan (W) 325, and very rarely Glutamine (Q) 325. ZnT8 autoantibodies may be specific to the R 325 or W 325 variant or maybe residue 325 non-specific. Sera that react with the Q allele only are extremely rare. The ELISA anti-ZnT8 ELISA Assay kit used in Diagnostiki Athinon is capable of detecting, and quantifying, autoantibodies specific to R 325 or to W 325, or to residue 325 non-specific variants.
