MuSK Antibody - Myasthenia Gravis Links
Last Modified on 09/16/2003
The following Links pertain to the newly discovered MuSK antibody in a significant percentage of myasthenics who are sero-negative for the AChR antibody. No opinions on that issue are expressed on this page and the links are those found using standard internet search procedures. Additional links will be added in the near future.
The following abstract is from the March/April 2003 American Academy of Neurology meeting.
1. [S50.002]
Muscle Specific Tyrosine Kinase (MuSK) Positive, Seronegative Myasthenia Gravis (SN-MG).
Clinical Characteristics and Response to Therapy
Donald B. Sanders, Durham, NC, Khalid El-Salem, Irbid, Jordan, Janice M. Massey, Durham,
NC, Angela Vincent, Oxford, United Kingdom
OBJECTIVE: To determine the clinical characteristics and response to treatment in
MG patients with anti-MuSK antibodies.
BACKGROUND: Anti-MuSK antibodies have been described in 40% to 70% of patients with
generalized SN-MG, but not in patients with ocular myasthenia or antibodies to the
acetylcholine receptor.
DESIGN/METHODS: Antibodies to rat MuSK were measured using a
radioimmunoprecipitation assay in serum from 27 consecutive patients with generalized
SN-MG, and in 10 with seropositive (SP) MG and 8 with ocular SN-MG.
RESULTS: Anti-MuSK antibodies were found in 10 of 27 patients with generalized
SN-MG, but not in 8 patients with ocular SN-MG or 10 with generalized SP-MG. All
MuSK-positive patients were female, with symptom onset between ages 21 and 49. Six had
prominent neck, shoulder or respiratory muscle weakness, and little or delayed ocular
muscle involvement. Jitter measurements by single fiber EMG confirmed a restricted
distribution of muscle involvement in several MuSK-positive patients, with relative
sparing of the forearm and facial muscles. Four had initial ocular and bulbar symptoms,
typical of MG.
Pyridostigmine produced some improvement in 5, none in 2, and worsening in 1. Thymectomy,
performed in 6, was not followed by improvement in any. Plasmapheresis produced marked
improvement in all 9 so treated. Prednisone produced improvement in 5 of 6 patients.
Neither of 2 patients who took azathioprine improved. Six of 8 patients had a good
response to cyclosporine, mycophenolate mofetil, or both.
CONCLUSIONS: Approximately 40% of our patients with generalized SN-MG had
antibodies for MuSK. The distribution of weakness in many MuSK positive patients was
atypical for MG, being limited to neck, shoulder and respiratory muscles, with little or
delayed ocular muscle involvement. Some patients did not respond well to commonly used
treatment modalities, but with selected therapy, all achieved a good clinical response.
Measurement of MuSK antibodies promises to be a valuable diagnostic test in patients with
SN-MG, and may be useful in selecting therapy.
Category - Muscle Disease/Neuromuscular Junction
SubCategory - Other
The following is a followup article:
Anti_MuSK Antibodies in Myasthenia Gravis by Dr. Donald
Sanders, Duke University
http://www.neurocast.com/site/content/sessions_07_2003.asp
Laboratory Testing for the MuSK antibody may be available from Athena Diagnostics in the United States http://www.athenadiagnostics.com/site/product_search/test_description_template.asp?id=227
The following links are other websites for MuSK and myasthenia.
1. From "Current Medicine"
http://www.rcpe.ac.uk/publications/articles/journal_32_1/07_myasthenia_gravis.pdf
The above is an Adobe Acrobat file.
2, From Dr. Vincent at Neurosciences
Group, Institute of Molecular Medicine, John Radcliffe Hospital, Oxford, UK
http://www.imm.ox.ac.uk/groups/neurosci/neuroimmuno.html
3, From Dr. Vincent at Neurosciences
Group, Institute of Molecular Medicine, John Radcliffe Hospital, Oxford, UK
http://www.ox.ac.uk/blueprint/2000-01/1904/17.shtml
4, From Dr. Werner Hoch at the Max
Planck Institute for Developmental Biology, Tübingen, Germany
http://www.bris.ac.uk/synaptic/research/pi/WH_res.html
5. From Dr. Vincent at Neurosciences
Group, Institute of Molecular Medicine, John Radcliffe Hospital, Oxford, UK Abstract from
a May 2002 presentation in Switzerland http://www.kenes.com/cholinergic/abstracts/118.doc
5a. The overall program for the Switzerland presentations is at:
http://www.kenes.com/cholinergic/wed.htm
6. A March 2001 press release from
Oxford University
http://www.admin.ox.ac.uk/po/010301.2.shtml
To submit addition links please send them to: stanley.way@prodigy.net