Detection of circRNA expression patterns in the PBMCs of AS and control groups
Using a CIRI-based computational pipeline, circRNAs present in RNA-seq data derived from the PBMCs of AS and control (CN) groups were predicted. In total, 10,441 distinct candidate circRNAs were detected in analyzed samples, of which 5,917 (56.7%) were known and 4,524 (43.3%) were novel in human samples. Overall, 3,432 circRNAs were present only in the AS group, 2,562 only in the CN group, and 4,447 present in both groups (Fig. 1A). Of these 10,441 circRNAs, 883 (8.46%) were derived from introns, 9,303 (89.1%) were generated from exonic sequences, and the remaining 255 (2.44%) were derived from intergenic regions. 10,186 different circRNAs originating from 3,968 parental genes were detected in these PBMCs samples, with 1,920 (48.4%) and 2,048 (51.4%) of the parental protein-coding genes producing one and more than one circRNA, respectively. A single gene encoding a phosphatidylinositol binding clathrin assembly protein was found to be the source of 32 different circRNAs in these samples (Fig. 1B). These circRNAs exhibited a chromosomal distribution pattern that was roughly consistent with chromosome size, and chromosomes 1, 2, and 3 produced the most circRNAs in these analyzed samples (Fig. 1C).