Anti–NF186 Antibodies

This laboratory assay detects IgG autoantibodies against NF186, a glycoprotein located at the node of Ranvier, the specialised structure that enables saltatory conduction along myelinated axons. NF186 is essential for nodal organisation and stability, working in concert with other proteins to maintain myelin integrity and efficient nerve transmission. Anti-NF186 antibodies (predominantly IgG4) are associated to an acute or subacute onset and can resemble Guillain–Barré syndrome or variants of CIDP. Patients typically show distal and proximal motor weakness (often symmetric, sometimes asymmetric) with sensory reduction; sensory ataxia and coarse tremor are less common than in anti-NF155 disease.

Electrophysiology shows a demyelinating pattern with or without axonal involvement; CSF protein may be elevated. Brachial plexus MRI is usually normal or only mildly altered. A rapid/subacute onset may lead to an initial GBS diagnosis, but the limited response to IVIG helps distinguish this form. Systemic corticosteroids are often effective, and targeted immunotherapies (e.g., rituximab) can be particularly beneficial.

In general, the form of autoimmune neuropathy associated with anti-NF186 antibodies, together with those associated with anti-NF155, anti-CNTN1 and anti-CASPR1 antibodies, respectively, falls into the category of “nodopathies” or “autoimmune paranodopathies,” a group of autoimmune neuropathies characterized by autoantibodies against node and paranode adhesion molecules. They have clinical characteristics that are quite distinct from classic CIDP. None show clear signs of inflammation or macrophage-mediated demyelination, and all respond poorly to specific treatments for CIDP.  This test is useful and essential in the differential diagnosis and therapeutic management of demyelinating neuropathies.