For example, ciRS-7 was found to be a natural microRNAs sponge for miRNA-7 and regulate Parkinson’s disease/Alzheimer’s disease-related genes; circPAIP2 is an intron-retaining circRNA which upregulates memory-related parental genes PAIP2 to affect memory development through PABP reactivation. This evidence concerns the gene PAIP2 and Parkinson disease.