Clinical utility of human leukocyte antigen genotyping and immunoglobulin G4 autoantibody testing in autoimmune neurological diseases: A focused minireview

The diagnosis of immunoglobulin G4 (IgG4)-related autoimmune neuropathies relies on a combination of clinical evaluation, imaging, and biological analyses, including serum and cerebrospinal fluid assessments. Several IgG4 autoantibodies have been described in these disorders, including muscle-specific kinase IgG4, leucine-rich glioma-inactivated 1 IgG4, nodo-paranodal IgG4, Ig-like domain-containing protein 5, anti-dipeptidyl-peptidase-like protein-6 antibodies, and contactin-associated protein-like 2 IgG4. Accurate identification of these autoantibodies using appropriate techniques is essential for optimizing diagnosis and guiding treatment selection. In addition, specific human leukocyte antigen (HLA) alleles and haplotypes are associated with the induction of these autoantibodies. This review summarizes current knowledge on the role of HLA alleles in regulating IgG4 autoantibody production and examines methods for detecting these autoantibodies, as well as their diagnostic and prognostic significance in IgG4-mediated neurological disorders.