VEGFA and triple-A syndrome: The hypoxic microenvironment results in the activation of hypoxia-inducible factor (HIF)-1, which can regulate the expression of several angiogenesis-related genes, including vascular endothelial growth factor (VEGF) and its receptors FLT-1, FLK-1, ANG-1, ANG-2, and TIE-2, thus affecting the state of AAA (Zimna and Kurpisz, 2015).