COL4A1 and hemorrhage: For instance, Col4a1 mutant mice have severe cerebrovascular disease and intracerebral hemorrhages; however, selective expression of mutant Col4a1 individually in vascular endothelial cells, pericytes or astrocytes each resulted in a very mild phenotype compared with that observed in Col4a1+/Δex41 mutants (Jeanne et al., 2015).