*3.3.2 Array based proteomics*

Array-based techniques can be divided into targeted assays that measure a select number of molecules, and Nucleic Acid Programmable Protein Arrays (NAPPA) arrays (**Table 4**). Targeted array-based techniques such as Enzyme-linked immunoassays (ELISA) and Luminex bead assays involve measurement of selected molecules based on the role of the molecule in a disease process and availability of the assay. These assays are limited by the number of protein markers that can be tested at once, yet a large number of samples can be tested. Array-based assays have been used to discover many candidate cytokines, chemokines, adhesion molecules, and receptors that may play a role in the development of T1D and its complications.

In contrast, NAPPA arrays provide high throughput information on thousands of candidate proteins in a more limited number of samples. NAPPA arrays contain imprinted gene on glass slides and a wheat germ expression system that converts the DNA to RNA to protein. This protein array then detects circulating levels of antibodies against the proteins in the blood of T1D individuals [53]. Recent studies by Bian et al. utilized NAPPA and ELISA to analyze more than 50% of the human proteome in the serum of recent onset T1D patients. They discovered six novel T1D-associated autoantibodies and created a combined AAb panel that had a higher AUC and sensitivity in diagnosis compared to the conventional AAb ZnT8A (**Table 5**) [8, 61]. More studies are required to confirm the findings utilizing the NAPPA in T1D.
