The use of eculizumab in ventilator-dependent myasthenia gravis patients.

INTRODUCTION/AIMS: Eculizumab has been shown to be efficacious in acetylcholine receptor antibody-positive (AChR+ ) Myasthenia Gravis Foundation of America (MGFA) class II, III, and IV generalized myasthenia gravis (gMG) patients. However, it has not been studied in MGFA class V gMG patients. METHODS: We report three AChR+ , refractory, MGFA class V gMG patients treated with eculizumab. MGFA class, MG-Composite (MGC) score and MG Activities of Daily Living (MG-ADL) score were assessed before and after eculizumab. RESULTS: Two of three gMG patients, refractory to intravenous immunoglobulin, plasmapheresis, prednisone, and (in one case) rituximab, showed a robust response to eculizumab with marked improvement in MGFA, MG-ADL, and MGC measures. The third patient showed a partial response to eculizumab but remained on noninvasive ventilation and gastrostomy intubation. Patients 1 and 2 achieved minimal manifestation status at week 4 and week 6, respectively, and showed continued improvement on MG-ADL and MGC scores through weeks 55 and 43, respectively, with eculizumab. The third patient showed a partial response at week 10, followed by a slight decline in his MG-ADL score, but noted a slow but an incomplete improvement afterward on MG-ADL and MGC scores, possibly due to delayed eculizumab infusion. DISCUSSION: Eculizumab may play a role in the treatment of patients with MGFA class V, refractory gMG. Larger studies are required to provide further evidence.

GNE Myopathy as a Myofibrillar Myopathy: Potential Important Disease Mechanism Implied by Muscle Biopsy.

We report a case of 2 sisters in their 20s with genetically confirmed UDP-N-acetylglucoasmine 2-epimerase/N-acetylmannosamine kinase myopathy along with muscle biopsy findings. Both patients described slowly progressive signs of distal-predominant weakness since adolescence that had been dismissed as "clumsiness." Exam and electrodiagnostic testing suggested a predominately distal myopathy. Muscle biopsy of the left tibialis anterior revealed rimmed vacuoles and, interestingly, also had characteristic features of a myofibrillar myopathy. Genetic testing confirmed a diagnosis of autosomal recessive GNE myopathy in both patients. GNE myopathy has not typically been considered a myofibrillar myopathy, but this case raises possibilities worthy of further exploration. It is possible that the unique combination of pathogenic alleles in GNE reported here has led to a novel form of GNE myopathy with muscle biopsy showing characteristic features of GNE myopathy and myofibrillar myopathy. The other possibility is that myofibrillar myopathy may be a more common feature of GNE myopathies than classically described.

Unilateral visual loss in a previously healthy 15-year-old girl: monosymptomatic neuromyelitis optica?

We report a previously healthy 15 year old girl with acute onset of unilateral visual loss consistent with a diagnosis of monosymptomatic optic neuritis. Her symptoms responded well to the use of high-dose intravenous methylprednisolone. With very brief follow-up (2 months) she has had no subsequent difficulties. However, testing was positive for the presence of anti-aquaporin-4 antibodies in both serum and cerebrospinal fluid, which have been associated with neuromyelitis optica (NMO). While NMO antibodies lack complete sensitivity, there is high degree of specificity. Our patient does not meet currently accepted diagnostic criteria for NMO, but is likely at high-risk to develop myelitis or recurrent optic neuritis. There are no evidence-based guidelines for whether this patient should undergo disease-modifying treatment. Based upon the high-risk for clinical relapse, we have recommended immunosuppressive therapy with rituximab (anti-B cell monoclonal antibodies). While randomized trials for patients with this clinical scenario are unlikely, observational studies of a cohort of such patients would provide better guidance on the natural history and merits of disease-modifying therapy.

Gap junction and purinergic P2 receptor proteins as a functional unit: insights from transcriptomics.

Gap junctions and purinergic P2 receptors (P2Rs) can be regarded as belonging to a common functional unit, given that they are involved in the transmission of calcium signals between cells. We have previously shown that deletion of the Gja1 gene alters expression levels of numerous genes encoding proteins with diverse functions, including purinergic receptors (P2Rs), and have found that genes synergistically or antagonistically expressed in wild-type tissues are more prone to be similarly or oppositely regulated in Cx43-nulls. We have now explored the use of coordination analysis of gene expression as a strategy to identify interlinked genes encoding functionally related proteins and pull-downs to evaluate their interlinkage. Our findings indicate that, in brain and in cultured astrocytes, several of these coexpressed genes encode proteins that are components of P2R signal-transduction pathways and/or directly interact with these receptors, including the gap junction protein connexin43 (Cx43) and Cx45 as well as pannexins. It is proposed that coordination analysis of gene expression may provide a novel unbiased strategy for the identification of proteins belonging to supramolecular complexes.