Endothelial dysfunction improved by l-arginine supplementation in the patient with Noonan syndrome, moyamoya-like vascular changes, and antiphospholipid syndrome. Y. Akita, S. Yatsuga, J. Nishioka, Y. Koga Dept Pediatrics & Child Health, Kurume Univ Sch Medicine, Kurume, Japan.

   We report a 12-year-old Japanese female with Noonan syndrome who had antiphospholipid syndrome and moyamoya-like vascular changes. She presented choreic movements in her face and extremities. She manifested clinical features that resemble those of Turner syndrome and has a normal karyotype. Tests for anticardiolipin antibody and lupus anticoagulant were positive. Magnetic resonance angiography revealed occlusion of bilateral internal carotid arteries and moyamoya-like vascular changes in the basal ganglion region. Moyamoya-like vascular changes are characterized by collateral vessels formation in the basal cerebral vasculature caused by chronic thrombosis or stenosis. We evaluated endothelial function in the patient by flow-mediated vasodilation (FMD) and found a significant decrease vs controls. We started l-Arginine supplementation therapy in the patient. l-Arginine is known to be an important precursor of nitric oxide (NO), which improved endothelial dysfunction in MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke) in our study. In this case, l-Arginine supplementation may reduce damage of focal brain ischemia by increasing microcirculation in cerebral blood flow(CBF).