Expression-based Genome-wide Association Study Links OPN and IL1-RA With Newly Diagnosed Type 1 Diabetes in Children

Context: Islet autoantibodies (IAbs) are currently the most reliable indicators of islet autoimmunity. However, IAbs do not fully meet the need for the prediction and intervention of type 1 diabetes (T1D). Serological proteins should be great sources for biomarkers. Objective: This work aimed to identify new proteomic biomarkers with the technology of an expression-based genome-wide association study (eGWAS) in children newly diagnosed with T1D. Methods: In an attempt to identify additional biomarkers, we performed an eGWAS using microarray data from 169 arrays of the pancreatic islets of T1D rodents (78 T1D cases and 91 controls). We ranked all 16 099 protein-coding genes by the likelihood of differential expression in the pancreatic islets. Our top 20 secreted proteins were screened in 170 children including 100 newly diagnosed T1D, and 50 type 2 diabetes (T2D) and 20 age-matched healthy children. With 6 proteins showing significance, we further conducted a validation study using the second independent set of 400 samples from children including 200 newly diagnosed with T1D, 100T2D, and 100 age-matched controls. Results: We identified 2 serum proteins that were significantly changed in T1 D vs both control and T2D, and 5 serum proteins were significantly changed both in T1D and T2D vs control. Serum osteopontin (OPN) levels were uniquely higher in T1D (T1 D vs controls, P = 1.29E-13 similar to 9.38E-7 T1D vs T2D, P = 2.65E-8 similar to 1.58E-7) with no difference between T2D and healthy control individuals. Serum interleukin 1 receptor antagonist (MA RA) levels were lower in T1D compared both with T2D (P= 3.36E-9 similar to 0.0236) and healthy participants (P= 1.09E-79 similar to 2.00E-12). Conclusion: Our results suggest that OPN and IL1-RA could be candidates for useful biomarkers for T1D in children.