As aberrant levels of HSPA2 have been associated in previous studies with human asthenozoospermia [51], the negative correlation between circEx3–6 and HSPA2 and reduced overall levels of circEx3-6 and circEx2-7 in asthenozoospermia suggest that circBoule RNAs may play an important role in human fertility. This evidence concerns the gene HSPA2 and Reduced sperm motility.