Dysregulation of the EphrinB2−EphB4 ratio in pediatric cerebral arteriovenous malformations is associated with endothelial cell dysfunction in vitro and functions as a novel noninvasive biomarker in patients

Blood vessels: untangling the causes of brain vessel malformations Tangled blood vessel growths in the brain, known as arteriovenous malformations (AVMs), can be identified with a urine test, and the test protein may also help in treatment. AVMs often have no symptoms and can go undiagnosed, but when they rupture they can cause deadly brain hemorrhage. Better diagnostic tools and nonsurgical treatments are needed. Katie Fehnel and Edward Smith at Boston Children’s Hospital, USA, and co-workers identified an imbalance in a pair of signal/receptor proteins called ephrins in AVMs. Disturbing the balance of ephrin levels in blood vessel-forming cells disrupted growth, causing disorganized vessel formation with too many sprouts and insufficient junctions. Testing ephrin levels in patients’ urine reliably identified AVMs. These results offer a rapid and noninvasive new diagnostic tool and may help find new treatments for this mostly invisible and potentially fatal condition.