Direct Antiglobulin test

Haematology

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Description

Patients with autoimmune encephalopathies may produce autoantibodies targeted towards neuronal surface antigens. Autoimmune encephalitis refers to a group of closely related diseases that share overlapping clinical features and have similar finding on brain imaging. The diseases can be differentiated by the presence of specific autoantibodies [1]. NMDAR (N-Methyl D-aspartate receptor) antibodies are glutamate receptor antibodies which may be associated with NMDA receptor encephalitis. AMPAR 1 and 2 (alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor 1 and 2) antibodies are also glutamate receptor antibodies . AMPAR antibodies can be observed in limbic encephalitis and atypical psychosis. LGI1 (Leucine rich glioma-inactivated protein 1) antibodies and GABA (gamma-aminobutyric acid) receptor antibodies may be also be associated with limbic encephalitis [2,3].CASPR2 (Contactin-associated Protein 2) antibodies can be seen in limbic encephalitis, neuromyotonia and Morvan's syndrome [2,3].The conditions present with symptoms such as seizures, confusion and other neuropsychiatric manifestations. Patients may have non-paraneoplastic or paraneoplastic associations. Diagnosis is usually made using a combination of clinical features, imaging and autoantibody detection. Early treatment results in considerable reduction of symptoms in most patients [1,2,3].

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Indications

To aid in the diagnosis of of autoimmune limbic encephalitis, neuromyotonia or Morvan's syndrome.

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Sample Type

1 x 6 mL EDTA

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Reference Range

Normal = Negative.

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Turnaround Time

Within 10 days

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Testing Frequency

Weekly

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External Notes

Patients with positive direct antiglobulin test results may need to be referred to NHSBT for further testing, advice will be given by blood bank at time of testing.

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References

Kelley BP, Patel SC, Marin HL, et al. Autoimmune Encephalitis: Pathophysiology and Imaging review of an overlooked diagnosis. American Journal of Neuroradiology. 2017. 38(6):1070-1078. [Ref 1]Lee SK. Lee ST. The laboratory diagnosis of autoimmune encephalitis. Journal of Epliepsy research. 2016. 6(2):45-52. [Ref 2].Lancaster E. The diagnosis and treatment of autoimmune encephalitis. 2016. 12(1):1-13. [Ref 3].

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See Also

Cerebellar antibodies; NMDAR Antibodies; VGKC Antibodies

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