Acetylcholine Receptor Anitbodies, AchR, ACR

Immunology

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Description

The acetylcholine receptor (ACR) is a membrane protein of about l0kDa. Autoantibodies to the acetylcholine receptor (ACRAb) have been shown to be a feature of myasthenia gravis (MG) and are probably responsible for much of its symptomatology [3]. They are found in the sera in over 80% of patients with this condition, including those with ocular myasthenia and the myasthenia syndrome induced by penicillamine, although in both these latter instances the antibody activity is generally weak and patients tend to be seronegative [1,4]. The level of antibody activity does not correlate well with the clinical severity of the disease. Repeated estimations of antibody activity are therefore not indicated [1]. The antibodies are absent in healthy subjects and patients with other neurological disorders and in the rare congenital form of the disease. Hence measurement of the antibody can be of considerable value in disease diagnosis. In patients with systemic MG, anti-MuSK (muscle-specific receptor tyrosine kinase) antibodies may be considered and are found in 20% of those patients lacking anti-ACR antibodies [2,4].

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Indications

Myasthenia Gravis and Thymic tumours.

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Sample Type

2mL Serum (Gel 5mL Yellow tube). Requests from outside Sheffield: Transport at ambient temperature via Royal Mail or Courier.

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Reference Range

Normal range is <0.2 nmol/L. Reference ranges established in house and PRU collaboration.

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Turnaround Time

Within 5 days

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Testing Frequency

Weekly

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References

PRU Handbook of Autoimmunity. 4th Edition. 2007. [Ref 1].Vincent A, and Leite MI. Neuromuscular junction autoimmune disease: muscle specific kinase antibodies and treatments for myasthenia gravis. Curr Opin Neurol. 2005. 18(5):519-525. [Ref 2].Hughes BW, Moro De Casillas ML, and Kaminski HJ. Pathophysiology of myasthenia gravis. Semin Neurol. 2004. 24(1):21-30. [Ref 3].Hoch W, et al. Auto-antibodies to the receptor tyrosine kinase MuSK in patients with myasthenia gravis without acetylcholine receptor antibodies. Nature Medicine. 2001. 7: 365-368. [Ref 4].

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See Also

MUSK; muscle antibodies

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