[Familial cerebral cavernomas: discovery made during an epileptic seizure in a 10-year-old girl]. / Cavernome cérébral familial: révélation par une épilepsie chez une fille de 10 ans.

The assessment of an epileptic seizure in a 10-year-old girl originating from Reunion Island revealed a case of familial cerebral cavernous angioma. Multiple hemorrhagic lesions seen during a cerebral magnetic resonance imaging (MRI) scan was suggestive of cavernomas. A cerebral MRI scan in the father showed multiple asymptomatic lesions, thus confirming the familial nature. A genetic study carried out on the patient and her father confirmed the presence of a mutation of the KRIT1 gene with an autosomal dominant transmission. In these disorders, an MRI scan in the patient's parents offers great diagnostic advantages. This screening leads to precautionary measures that are easy to put in place.

Serpentine stability to mantle depths and subduction-related magmatism.

Results of high-pressure experiments on samples of hydrated mantle rocks show that the serpentine mineral antigorite is stable to approximately 720 degrees C at 2 gigapascals, to approximately 690 degrees C at 3 gigapascals, and to approximately 620 degrees C at 5 gigapascals. The breakdown of antigorite to forsterite plus enstatite under these conditions produces 13 percent H(2)O by weight to depths of 150 to 200 kilometers in subduction zones. This H(2)O is in an ideal position for ascent into the hotter, overlying mantle where it can cause partial melting in the source region for calc-alkaline magmas at a depth of 100 to 130 kilometers and a temperature of approximately 1300 degrees C. The breakdown of antigorite in hydrated mantle produces an order of magnitude more H(2)O than does the dehydration of altered oceanic crust.