LGI1 and CASPR2 Antibodies

These are two proteins that have been shown to form part of the Voltage gated Potassium channel complex (VGKC).

Antibodies to either of these two proteins have been shown to produce a clinical phenotype.

• LGI1 antibodies are associated with Facial brachial dystonic seizures (FBDS), a sub type of limbic encephalitis
• CASPR2 antibodies are associated with Morvans syndrome, a sub type of limbic encephalitis

Traditionally a screening assay has been used to test for all VGKC antibodies (testing of patient serum binding to purified rabbit brain VGKC protein, via a radioimmunoprecipitation (RIA)method).

Clinical studies looking at the outcome for patients who show positive VGKC antibodies by RIA but who are negative for LGI1 or CASPR by IIF, have found that these patients predominantly have a generic autoimmune / inflammatory phenotype, rather than true limbic encephalitis (Van Sonderen et al 2016, Yeo et al 2018).

In light of these findings, from 19 October 2020, the Oxford Immunology Laboratory is recommending that LGI1 / CASPR2 antibody testing is conducted as a first line test when investigating a patient for VGKC antibodies.

1) van Sonderen A et al. The relevance of VGKC positivity in the absence of LGI1 and Caspr2 antibodies. Neurology. 2016;86(18):16921699. doi:10.1212/WNL.0000000000002637

2) Yeo T et al Distinction between anti-VGKC-complex seropositive patients with and without anti-LGI1/CASPR2 antibodies. J Neurol Sci. 2018;391:64-71. doi:10.1016/j.jns.2018.05.020

Specimen requirements

Serum 1ml; CSF not required but can be analysed

Cost

80 UKP - UK NHS, International and Private

Laboratory turnaround time

14 days

Laboratory method

Cell based assay

Reference range/units

Not applicable

Associated tests

Not applicable

Sample stability

4 months at 2-8ºC

Shipping and storage

UK and Ireland

Ambient temperature and first class post. Hays DX users please enquire via email below.

International

Ambient temperature if courier will deliver within 72 hours otherwise consider refrigerated transport. Freezing is not a requirement.

Ensure delivery Monday to Friday 09:00 - 17:30.

Further information and contact details

For further information, email immunology.office@nhs.net