Neurophysiological and mitochondrial abnormalities in MuSK antibody seropositive myasthenia gravis compared to other immunological subtypes
2006 (English)In: Clinical Neurophysiology, ISSN 1388-2457, E-ISSN 1872-8952, Vol. 117, no 7, 1434-1443 p.Article in journal (Refereed) Published
Objective: To compare the electrophysiological and histopathological features of immunological myasthenia gravis (MG) subtypes.Methods: Fifty MG patients underwent clinical examination, MuSK-Ab and AChR-Ab analysis. The majority underwent quantitative andsingle-fiber electromyography (QEMG, SFEMG), repetitive nerve stimulation and deltoid muscle biopsy. From muscle specimens withhistological mitochondrial dysfunction, we amplified mitochondrial DNA (mtDNA). In specimens with mtDNA deletions, the nuclear genePOLG1 was sequenced.Results: Five AChR-Ab seropositive [AChR(C)] and 5 seronegative [AChR(K)] patients were MuSK-Ab seropositive [MuSK(C)]. Five of7 neurophysiologically examined MuSK(C) patients (71%) had proximal myopathic pattern, compared to 7 of 31 MuSK(K)/AChR(C)patients (23%) (PZ0.012). SFEMG was abnormal in all examined MuSK(C) patients. All 7 biopsied MuSK(C) and 32 MuSK(K) patients(89%) had cytochrome c oxidase (COX) negative fibers. Three of five MuSK(C) and 13 of 20 MuSK(K) patients analyzed had multiplemtDNA deletions but no POLG1 mutations.Conclusions: Similar degree of SFEMG abnormalities was present in proximal muscles among MuSK(C) and AChR(C) patients. Proximalmyopathy was over-represented in MuSK(C) patients; however, both MuSK(C) and MuSK(K) patients had mild myopathy with frequentmitochondrial abnormalities.Significance: The weakness in MuSK(C) patients is most likely due to disturbed neuromuscular transmission. The frequently encounteredmitochondrial dysfunction in MG warrants further study.
Place, publisher, year, edition, pages
2006. Vol. 117, no 7, 1434-1443 p.
Myasthenia gravis, Quantitative EMG, Single-fiber EMG, MuSK, Myopathy, mtDNA deletions
Medical and Health Sciences
IdentifiersURN: urn:nbn:se:uu:diva-95260DOI: 10.1016/j.clinph.2006.03.028ISI: 000239227100004OAI: oai:DiVA.org:uu-95260DiVA: diva2:169408