Capillary Malformation–Arteriovenous Malformation andRASA1Mutations

Abstract

Capillary malformation–arteriovenous malformation (CM–AVM) is a subtype of CM that is inherited as an autosomal‐dominant disorder. Patients typically have multiple small pinkish‐reddish CMs, often with a halo. These lesions are randomly distributed on the body. About 15–20% of patients have an associated arteriovenous fistula or malformation often located on head and neck. The fast‐flow lesions involve skin, subcutaneous tissue, muscle and/or bone or the brain or the spine. Parkes Weber syndrome and vein of Galen aneurysmal malformation are also part of CM–AVM. Most CM–AVM patients have a detectable RASA1 mutation causing loss‐of‐function of p120RASGAP, a guanosine triphosphatase‐activating protein, which participates in the regulation of the Ras signalling pathway. Most mutations are private and no genotype–phenotype correlation has been identified. A somatic second hit is likely necessary to produce lesional, complete loss‐of‐function of p120RASGAP, as the malformations are localised, and often multifocal. Ras‐pathway modulators may provide futuristic therapies for CM–AVM. Key Concepts: Multifocal, often small, capillary malformations may be hereditary. Lesions with pale reddish‐brownish colour, a halo and/or a good demarcation line suggest CM–AVM. Numerous miliary telangiectasias (often on extremities) are also suggestive of CM–AVM. Many, but not all patients, also have a fast‐flow lesion. Distribution of fast‐flow lesions differs from that of hereditary haemorrhagic telangiectasia. Until better statistics exist, clinical examination should include T1/T2 brain MRI, when molecular diagnosis is confirmed. These CMs do not respond well to current lasers. RASA1 ‐dominant mutations are mostly private, that is, specific to each family. Parkes Weber syndrome patients with CMs elsewhere on the body are likely to carry a RASA1 mutation. Family history is not necessarily present, as de novo mutations occur.

MicroRNA Control of Vascular Endothelial Growth Factor Signaling Output During Vascular Development

“…MiR-132 was found to be highly expressed in tumor ECs, but not in normal ECs, and its induction is driven by angiogenic factors such as Vegf and Fgf2 64 . Silencing of miR-132 expression decreases the miR-132 target, p120RasGAP 65 , which negatively regulates Ras, and contributes to vascular development and remodelling 66 . Induction of miR-132 expression in ECs may act as an angiogenic switch during tumor neovascularization, and antagonism of miR-132 markedly decreases tumor angiogenesis in mouse models 64 .…”