Differential piRNAs expression levels were also detected between severe and mild ASD cases, with piR-hsa-22380, piR-hsa-28131, piR-hsa-27134, and piR-hsa-27138 being the most upregulated piRNAs and piR-hsa-27623 and piR-hsa-32175 being the most downregulated piRNAs in children with severe autism [41]. This evidence concerns the gene PIR and autism.