Myelin Associated Glycoprotein Antibodies (ANTI-MAG)

Immunology

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Description

Myelin associated glycoprotein ( MAG ) is found in central and peripheral nervous system myelin. MAG appears on oligodendrocytes and Schwann cells. The localisation of MAG in the peripheral region in myelin suggests that MAG may participate in neuron-glial cell interaction that leads to myelination. This hypothesis is supported by the observation that MAG antibodies may lead to demyelination. MAG antibodies are believed to be pathogenic [1]. IgM autoantibodies against MAG are found in sensory motor neuropathies and IgM paraprotein associated neuropathies. The determination of MAG antibodies helps to separate IgM associated neuropathies from other commonly acquired polyneuropathies ( e.g. chronic inflammatory demyelinating polyneuropathy ). Both disorders may be slowly progressive and appear as a predominantly demyelinating neuropathy by electrophysiological and morphological studies. Also, both may have an elevated CSF protein concentration and may respond to immunosuppressive therapy. MAG antibodies have occasionally been found in multiple sclerosis and myesthenia gravis [2].

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Indications

Chronic sensory motor neuropathy.

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Sample Type

2mL Serum ( Gel 5mL Yellow tube ). Requests from outside Sheffield: Freeze sample prior to dispatch and transport frozen sample at ambient temperature via Royal Mail or Courier ( dry ice not required ).

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Reference Range

<1000 BTU.

Reference range established by manufacturer and verified in house.

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Turnaround Time

Within 10 days

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Testing Frequency

Alternate weeks

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External Notes

Separate and Freeze immediately ( IgM Anti-MAG is labile ).

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References

Steck AJ, Stalder AK and Renaud S. Anti-myelin associated glycoprotein neuropathy. Curr Opin Neurol. 2006. 19( 5 ): 458-463. [Ref 1]
Polman CH, Killestein J. Anti-myelin antibodies in multiple sclerosis; clinically useful? Journal of Neurology, Neurosurgery and Psychiatry. 2006. 176( 1-2 ): 106-114. [Ref 2]
Nobile-Orazio E, Marinella C. Neuropathy and monoclonal gammopathy. Curr. Opin. Neurology. 2001. 14( 5 ):615-620.
Nobile-Orazio E, et al. Frequency and clinical correlates of anti-neural IgM antibodies in neuropathy associated with IgM monoclonal gammopathy. Ann. Neurol. 1994. 36: 416-424.

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