Despite the facts that (1) advanced age is a major risk factor for AAAs [14], (2) VSMC senescence correlates with increased level of reactive oxygen species (ROS) [15], and (3) Klf5 participates in development and progression of AAAs [13], it remains to be clarified whether and how Klf5 mediates the mechanistic and functional link between ROS generation and VSMC senescence. This evidence concerns the gene KLF5 and achalasia-alacrima syndrome.