Diagnostic dilemma: Sturge-Weber syndrome, without facial nevus

ABSTRACTSturge-Weber syndrome (SWS), a rare sporadic neurocutaneous disease, is characterized by a congenital unilateral port-wine nevus affecting the area innervated by V1, ipsilateral leptomeningeal angiomatosis, and calcification in the occipital or frontoparietal region and glaucoma/vascular eye abnormality. Three types of SWS have been described in literature: Type I (classic) demonstrates facial and leptomeningeal angioma, often with glaucoma; type II has facial angioma and glaucoma, with no evidence of intracranial lesions; and type III (rarest) presents with only leptomeningeal angioma. Only a few cases of type III SWS have been reported. Here, we report a case of a seven-year-old boy with focal complex partial seizure, who was diagnosed with SWS without facial nevus. Recognition of this type of SWS is important, as our patient had been misdiagnosed and received inappropriate antiepileptic drugs for six years. We suggest that in the appropriate clinical scenario, the diagnosis of SWS without facial nevus should be considered before labelling idiopathic or cryptogenic localization-related epilepsy, and gadolinium-enhanced magnetic resonance imaging (MRI) should be done in clinically suspicious cases of SWS, without facial nevus.

Myosin II directly binds and inhibits Dbl family guanine nucleotide exchange factors: a possible link to Rho family GTPases

Cell migration requires the coordinated spatiotemporal regulation of actomyosin contraction and cell protrusion/adhesion. Nonmuscle myosin II (MII) controls Rac1 and Cdc42 activation, and cell protrusion and focal complex formation in migrating cells. However, these mechanisms are poorly understood. Here, we show that MII interacts specifically with multiple Dbl family guanine nucleotide exchange factors (GEFs). Binding is mediated by the conserved tandem Dbl homology–pleckstrin homology module, the catalytic site of these GEFs, with dissociation constants of ∼0.3 µM. Binding to the GEFs required assembly of the MII into filaments and actin-stimulated ATPase activity. Binding of MII suppressed GEF activity. Accordingly, inhibition of MII ATPase activity caused release of GEFs and activation of Rho GTPases. Depletion of βPIX GEF in migrating NIH3T3 fibroblasts suppressed lamellipodial protrusions and focal complex formation induced by MII inhibition. The results elucidate a functional link between MII and Rac1/Cdc42 GTPases, which may regulate protrusion/adhesion dynamics in migrating cells.