COL4A1 and hemorrhagic stroke: Notably, observations made with certain semi-dominant mutant forms of collagen Col4a1/a2 from Caenorhabditis, mice or human patients with vasculature-related diseases such as hemorrhagic stroke led to the suggestion that particular mutations, most often changing the glycine of a Gly-X-Y repeat, may interfere with the folding and eventually secretion of the heterotrimeric collagen molecule as a whole and may potentially affect also the secretion of other molecules [28,41,55-57].