Objectives To determine whether glycine receptor α1 subunit-specific autoantibodies (GlyRα1-IgG) occur in a broader spectrum of brainstem and spinal hyperexcitability disorders than the progressive encephalomyelitis with rigidity and myoclonus phenotype recognized to date, and to ascertain disease specificity.
Design Retrospective, case-control study.
Settings Mayo Clinic, Rochester, Minnesota, and University of Barcelona, Spain.
Patients Eighty-one patients with stiff-man syndrome phenotype, 80 neurologic control subjects, and 20 healthy control subjects.
Intervention Glycine receptor α1–transfected cells to test serum or cerebrospinal fluid from cases and control subjects.
Main Outcome Measures Frequency of GlyRα1-IgG positivity among stiff-man syndrome phenotype cases and control subjects. Comparison of GlyRα1-IgG seropositive and seronegative cases.
Results Seropositive cases (12% of cases) included 9 with stiff-man syndrome (4 classic; 5 variant; 66% were glutamic acid decarboxylase 65–IgG positive) and 1 with progressive encephalomyelitis with rigidity and myoclonus. Immunotherapy responses were noted more frequently in GlyRα1-IgG–positive cases (6 of 7 improved) than in seronegative cases (7 of 25 improved; P = .02). The single seropositive control patient had steroid-responsive vision loss and optic atrophy with inflammatory cerebrospinal fluid.
Conclusions Glycine receptor α1–IgG aids identification of autoimmune brainstem/spinal cord hyperexcitability disorders and may extend to the glycinergic visual system.