1/4. mutation causing congenital myasthenia reveals acetylcholine receptor beta/delta subunit interaction essential for assembly.We describe a severe postsynaptic congenital myasthenic syndrome with marked endplate acetylcholine receptor (AChR) deficiency caused by 2 heteroallelic mutations in the beta subunit gene. One mutation causes skipping of exon 8, truncating the beta subunit before its M1 transmembrane domain, and abolishing surface expression of pentameric AChR. The other mutation, a 3-codon deletion (beta426delEQE) in the long cytoplasmic loop between the M3 and M4 domains, curtails but does not abolish expression. By coexpressing beta426delEQE with combinations of wild-type subunits in 293 HEK cells, we demonstrate that beta426delEQE impairs AChR assembly by disrupting a specific interaction between beta and delta subunits. Studies with related deletion and missense mutants indicate that secondary structure in this region of the beta subunit is crucial for interaction with the delta subunit. The findings imply that the mutated residues are positioned at the interface between beta and delta subunits and demonstrate contribution of this local region of the long cytoplasmic loop to AChR assembly.- - - - - - - - - - ranking = 1keywords = myasthenia (Clic here for more details about this article) |
2/4. Surgical correction of blepharoptosis in patients with myasthenia gravis.PURPOSE: To describe the results of surgical correction of blepharoptosis in a series of patients with myasthenia gravis. methods: We reviewed the medical records of all patients with myasthenia gravis who underwent surgical correction for blepharoptosis at the Mayo Clinic between 1985 and 1999. The primary outcome measure was change in interpalpebral eyelid fissure height. RESULTS: Eighteen blepharoptosis procedures were performed on 11 patients with myasthenia gravis. Eight of the 11 patients had ocular myasthenia gravis, and 3 had systemic myasthenia gravis. Of the 18 procedures performed, 11 were external levator advancements (ELA), 6 were frontalis slings, and 1 was a tarsomyectomy. patients were followed up postoperatively for an average of 34 months (range, 9 to 126 months). The amount of ptosis was quantified preoperatively and postoperatively for 9 of the 11 eyelids that underwent ELA. For these eyelids, there was a statistically significant improvement in the mean interpalpebral eyelid fissure height, from 4.2 mm preoperatively to 8.1 mm postoperatively, with a mean difference of 3.9 mm (95% confidence interval, 2.3 to 5.5 mm; P = .0005). postoperative complications included worsened diplopia in 1 patient who underwent ELA and exposure keratopathy in 1 patient who underwent a frontalis sling procedure. Two of the eyelids that underwent ELA developed recurrent ptosis, requiring additional surgery more than 2 years after the initial procedure. CONCLUSION: Surgical correction of blepharoptosis is an appropriate treatment option in patients with myasthenia gravis who fail medical therapy. Potential complications include worsened diplopia and exposure keratopathy.- - - - - - - - - - ranking = 8.1193895454571keywords = myasthenia gravis, myasthenia, gravis (Clic here for more details about this article) |
3/4. Akinesia, arthrogryposis, craniosynostosis: a presentation of neonatal myasthenia with fetal onset.Major akinesia with arthrogryposis and craniosynostosis at birth mimics irreversible disorders of the nervous system of pejorative outcome. In this context, the early detection of anti-acetylcholine fetal receptor antibodies in the mother may allow rapid diagnosis of transient neonatal myasthenia of favorable prognosis.- - - - - - - - - - ranking = 1.25keywords = myasthenia (Clic here for more details about this article) |
4/4. Seronegative neonatal myasthenia gravis in one of the twins.Neonatal myasthenia gravis has been described as a transient condition affecting only a small percent of neonates. We report a twin gestation in a seronegative mother with myasthenia gravis, in which only one twin was affected.- - - - - - - - - - ranking = 4.8716337272743keywords = myasthenia gravis, myasthenia, gravis (Clic here for more details about this article) |