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An aneurysm is an abnormal enlargement or bulging of the wall of a blood vessel. Most
often, aneurysms occur in large blood vessels - the aorta (Thoracic Aortic Aneurysm (TAA) and
Abdominal Aortic Aneurysm (AAA) and brain vessels (Intracranial Aneurysm (IA)). Despite the
presence of significant differences in the pathogenesis of the development and progression of IA
and TAA/AAA, there are also similarities. For instance, both have been shown to be strongly influenced
by shear stress, inflammatory processes, and enzymatic destruction of the elastic lamellae
and extracellular matrix (ECM) proteins of the vascular wall. Moreover, although IA and TAA are
predominantly considered arteriopathies with different pathological mechanisms, they share risk
factors with AAA, such as hypertension and smoking. However, there is a need for a more in-
-depth study of the key elements that may influence the formation and progression of a particular
aneurysm to find ways of therapeutic intervention or search for a diagnostic tool. Today, it is
known that the disruption of gene expression is one of the main mechanisms that contribute to the
development of aneurysms. At the same time, growing evidence suggests that aberrant epigenetic
regulation of gene function is strongly related to the genesis of aneurysms. Although much has
been studied of the known protein-coding genes, circular RNAs (circRNAs), a relatively new and
rapidly evolving large family of transcripts, have recently received much scientific attention. CircRNAs
regulate gene expression through the sponging of microRNAs (miRNAs) and can also be
used as therapeutic targets and biomarkers. Increasing evidence has implicated circRNAs in the
pathogenesis of multiple cardiovascular diseases, including the development of aneurysms. However,
the mechanism of dysregulation of certain circRNAs in a particular aneurysm remains to be
studied. The discovery of circRNAs has recently advanced our understanding of the latest mode of
miRNAs/target genes regulation in the development and progression of IA and TAA/AAA. The
aim of this study is to compare the expression profiles of circRNAs to search for similar or different
effects of certain circRNAs on the formation and progression of IA and TAA/AAA.
