Alternative exon usage is an important mechanism for generating transcript diversity20,21. Using the splicing ANOVA and splicing index algorithm with conservative criteria (FDR<0.01 with a minimum 2-fold splice index difference between at least two regions/areas or periods; Supplementary Information 6.5), we found that 13,647 of 15,132 (90.2%) expressed genes exhibited DEU across sampled regions (0.1%), periods (19.5%), or both (70.6%). Of 14,375 NCX genes, 88.7% exhibited DEU across sampled areas (<0.01%), periods (59.8%), or both (28.9%). The regulation of DEU also varied across time, with the vast majority of expressed genes (83.0%) exhibiting temporal DEU across fetal development, while only 0.9% and 1.4% were temporally regulated across postnatal development and adulthood, respectively.
