circRNAs microarray analysis in plasma of Parkinson’s Disease

Parkinson's disease (PD) is a chronic and progressive degenerative disease of the central nervous system. Degenerative neuropathy can occur in patients with PD even before typical clinical symptoms appear in the preclinical stage. Therefore, if the early diagnosis of degenerative diseases can be timely and the correlation with the disease progression can be explored, the disease progression will be slowed down and the quality of life of patients will be improved. In this study, the circRNA microarray was employed to screen the dysregulated circRNA in plasma samples of PD CapitalBio Technology Human CircRNA Array v2 was designed with four identical arrays per slide (4 x 180K format), with each array containing probes interrogating about 170,340 human circRNAs. Those circRNA target sequences were all from Circbase，Deepbase and Rybak-Wolf20151. Each circRNA was simultaneous detected by a long probe and a short probe. The circRNA array also contain 4974 Agilent control probes.The circRNA array data were analyzed for data summarization, normalization and quality control by using the GeneSpring software V13.0 (Agilent). To select the differentially expressed genes, we used threshold values of ≥2 and ≤−2-fold change and a Benjamini-Hochberg corrected p vlaue of 0.05. The data was Log2 transformed and median centered by genes using the Adjust Data function of CLUSTER 3.0 software then further analyzed with hierarchical clustering with average linkage (Eisen et al., 1998). Finally, we performed tree visualization by using Java Treeview (Stanford University School of Medicine, Stanford, CA, USA).