LGI1 (leucine-rich glioma-inactivated 1) antibody is associated with autoimmune encephalitis, a neurological disorder characterized by inflammation of the brain. Discovered in 2010. LGI1 is a secreted neuronal protein that interacts with presynaptic ADAM23 and postsynaptic ADAM22. forming a trans-synaptic complex involved in synaptic transmission and plasticity. Antibodies targeting LGI1 disrupt this interaction, leading to neuronal hyperexcitability.
LGI1 antibody encephalitis predominantly affects adults, with a slight male predominance. Clinical features include faciobrachial dystonic seizures (FBDS), memory deficits, confusion, and psychiatric symptoms. FBDS, brief involuntary movements of the face and arm, are pathognomonic and often precede cognitive decline. Hyponatremia is a common laboratory finding.
Diagnosis relies on detecting LGI1 antibodies in serum or cerebrospinal fluid (CSF) using cell-based assays. Early immunotherapy (steroids, IVIG, or plasma exchange) improves outcomes, though residual cognitive deficits may persist. Unlike other autoimmune encephalitides (e.g., anti-NMDAR), LGI1 antibodies are typically IgG4 subclass and not strongly linked to underlying tumors.
Research suggests genetic susceptibility (e.g., HLA-DR7 haplotype) and molecular mimicry as potential mechanisms. However, the exact pathophysiology remains unclear. Current studies focus on long-term outcomes, biomarker validation, and targeted therapies. LGI1 antibody encephalitis exemplifies the intersection of autoimmunity and neurology, emphasizing early recognition for optimal management.