Immunofluorescence analyses revealed a reduced expression of both claudin-5 and occludin in the blood vessels of bAVMs compared to the corresponding perilesional zone (p-value < 0.05), while these differences were not observed in the CCM samples (Figure 1 and Figure 2 and Supplementary Figures S2 and S3). This evidence concerns the gene OCLN and cerebral cavernous malformation.