title: Biology of vascular malformations of the brain.
abstract: OBJECTIVE
  This review discusses recent research on the genetic, molecular, cellular, and developmental mechanisms underlying the etiology of vascular malformations of the brain (VMBs), including cerebral cavernous malformation, sporadic brain arteriovenous malformation, and the arteriovenous malformations of hereditary hemorrhagic telangiectasia. Summary of Review- The identification of gene mutations and genetic risk factors associated with cerebral cavernous malformation, hereditary hemorrhagic telangiectasia, and sporadic arteriovenous malformation has enabled the development of animal models for these diseases and provided new insights into their etiology. All of the genes associated with VMBs to date have known or plausible roles in angiogenesis and vascular remodeling. Recent work suggests that the angiogenic process most severely disrupted by VMB gene mutation is that of vascular stabilization, the process whereby vascular endothelial cells form capillary tubes, strengthen their intercellular junctions, and recruit smooth muscle cells to the vessel wall. In addition, there is now good evidence that in some cases, cerebral cavernous malformation lesion formation involves a genetic 2-hit mechanism in which a germline mutation in one copy of a cerebral cavernous malformation gene is followed by a somatic mutation in the other copy. There is also increasing evidence that environmental second hits can produce lesions when there is a mutation to a single allele of a VMB gene.
  
  
  CONCLUSIONS
  Recent findings begin to explain how mutations in VMB genes render vessels vulnerable to rupture when challenged with other inauspicious genetic or environmental factors and have suggested candidate therapeutics. Understanding of the cellular mechanisms of VMB formation and progression in humans has lagged behind that in animal models. New knowledge of lesion biology will spur new translational work. Several well-established clinical and genetic database efforts are already in place, and further progress will be facilitated by collaborative expansion and standardization of these.
authors.affiliation: National Institute of Neurological Disorders and Stroke, Bethesda, Md., USA. QHRTS21@gmail.com
authors.forename: Gabrielle G
authors.initials: GG
authors.lastname: Leblanc
authors.forename: Eugene
authors.initials: E
authors.lastname: Golanov
authors.forename: Issam A
authors.initials: IA
authors.lastname: Awad
authors.forename: William L
authors.initials: WL
authors.lastname: Young
mesh_terms: D000818:Animals; D002536:Cerebral Arteries / Q000002:abnormalities* / Q000473:pathology / Q000503:physiopathology*; D004195:Disease Models, Animal; D018507:Gene Expression Regulation, Developmental / Q000235:genetics; D020022:Genetic Predisposition to Disease / Q000196:embryology*; D020786:Hemangioma, Cavernous, Central Nervous System / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology; D006801:Humans; D002538:Intracranial Arteriovenous Malformations / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology*; D009154:Mutation / Q000235:genetics; D009389:Neovascularization, Pathologic / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology*; D013683:Telangiectasia, Hereditary Hemorrhagic / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology