Although there was minimal PAI‐1 expression in normal brain (Figure 3b), AVMs and CCMs expressed abundant PAI‐1 in both PECAM‐positive regions and throughout the lesions, as shown for representative AVMs (Figure 3 [d, f, h, and j]) and CCM (Figure 3 [l and n]). This evidence concerns the gene SERPINE1 and cerebrocostomandibular syndrome.