Gene is likely cause of stroke-inducing vascular mal...( UCSF scientists have discovered that...)

UCSF scientists have discovered that a gene controlling whether blood vessels differentiate into arteries or veins during embryonic development is linked to a vascular disorder in the brain that causes stroke.

The UCSF studies were done in mice, and the new findings are the first to provide information on both the progression and regression of this particular brain disorder, known as BAVM, and to provide molecular clues into the disease, which is not well-understood and chiefly affects young people.

BAVM, for brain arteriovenous malformation, is a vascular disorder causing arteries and veins to be directly connected, rather than through capillaries. This direct connection produces enlarged, tangled masses of vessels that are prone to hemorrhagic rupture, bleeding and stroke. Because they develop most often in growing tissues, BAVMs are responsible for half of the hemorrhagic strokes in children.

Study findings were published in a recent issue (Aug. 5, 2008) of the Proceedings of the National Academy of Sciences.

The UCSF team identified the gene, known as Notch, as a potential cause of BAVMs because of its role in directing embryonic blood vessel formation. Using genetic tools, the team "turned on" a constantly active Notch gene in endothelial brain cells, which are the cells lining blood vessels in the brain, and found that BAVMs were induced. When researchers turned the gene off, the mice exhibited full recovery from the disease's progression.

"This was exciting. The activated Notch gene caused BAVM in all of the mice, making it an unprecedented, potent molecular lesion in the induction of the pathology," said Rong Wang, PhD, senior author on the study, associate professor and director of the Laboratory for Accelerated Vascular Research and Mildred V. Strouss Endowed Chair in Vascular Surgery at UCSF. "Furthermore, we found that repression of the gene in already-ill mice led to their recovery."