Genomic Unit for the Diagnosis of Human Pathologies, Center for Translational Genomics and Bioinformatics, San Raffaele Scientific Institute, Milan, Italy.
Clin Chem. 2011 Dec;57(12):1693-702. doi: 10.1373/clinchem.2011.170662. Epub 2011 Oct 6.
Zinc transporter 8 (ZnT8) is a recently identified major autoantigen in type 1 diabetes, and autoantibodies to ZnT8 (ZnT8A) are new markers for disease prediction and diagnosis. Here we report the results of the first international proficiency evaluation of ZnT8A assays by the Diabetes Antibody Standardization Program (DASP).
After a pilot workshop in 2007, an expanded ZnT8A workshop was held in 2009, with 26 participating laboratories from 13 countries submitting results of 63 different assays. ZnT8A levels were measured in coded sera from 50 patients with newly diagnosed type 1 diabetes and 100 blood donor controls. Results were analyzed comparing area under the ROC curve (ROC-AUC), sensitivity adjusted to 95% specificity (AS95), concordance of sample ZnT8A positive or negative designation, and autoantibody levels.
ZnT8A radio binding assays (RBAs) based on combined immunoprecipitation of the 2 most frequent ZnT8 COOH-terminal domain polymorphic variants showed a median ROC-AUC of 0.848 [interquartile range (IQR) 0.796-0.878] and a median AS95 of 70% (IQR 60%-72%). These RBAs were more sensitive than assays using as antigen either 1 ZnT8 variant only or chimeric constructs joining NH(2)- and COOH-terminal domains, assays based on immunoprecipitation and bioluminescent detection, or assays based on immunofluorescent staining of cells transfected with full-length antigen.
The DASP workshop identified immunoprecipitation-based ZnT8A assays and antigen constructs that achieved both a high degree of sensitivity and specificity and were suitable for more widespread clinical application.
锌转运蛋白 8（ZnT8）是 1 型糖尿病中最近确定的主要自身抗原，针对 ZnT8 的自身抗体（ZnT8A）是疾病预测和诊断的新标志物。在此，我们报告了糖尿病自身抗体标准化计划（DASP）首次对 ZnT8A 检测进行的国际能力验证的结果。
在 2007 年的一次试点研讨会上，2009 年又举行了一次扩大的 ZnT8A 研讨会，来自 13 个国家的 26 个参与实验室提交了 63 种不同检测方法的结果。对 50 例新诊断的 1 型糖尿病患者和 100 名献血者对照的编码血清进行了 ZnT8A 水平的测量。比较了 ROC 曲线下面积（ROC-AUC）、调整到 95%特异性的灵敏度（AS95）、样本 ZnT8A 阳性或阴性标记的一致性以及自身抗体水平。
基于对最常见的 ZnT8 COOH 末端结构域多态性变体进行联合免疫沉淀的 ZnT8 放射结合分析（RBA）显示，ROC-AUC 的中位数为 0.848（四分位距 [IQR] 0.796-0.878），AS95 的中位数为 70%（IQR 60%-72%）。这些 RBA 比仅使用 1 种 ZnT8 变体作为抗原或使用 NH2-和 COOH 末端结构域的嵌合构建体、基于免疫沉淀和生物发光检测的检测法、或基于全长抗原转染细胞的免疫荧光染色的检测法更敏感。
DASP 研讨会确定了基于免疫沉淀的 ZnT8A 检测法和抗原构建体，这些检测法既具有高度的敏感性和特异性，又适合更广泛的临床应用。
