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Anti-IGLON5 disease: A new case without neuropathologic evidence of brainstem tauopathy
Maria Elena Erro1, Lidia Sabater2, Laura Martínez2
1From the Neurology Department (M.E.E., L.M., M.H., A.O.), Complejo Hospitalario de Navarra, Navarra Institute for Health Research (IdiSNA), Pamplona; Neuroimmunology Program (L.S., F.G.), Institut d'Investigació Biomèdica August Pi i Sunyer (IDIBAPS), Hospital Clinic, Barcelona; Neurophysiology Department (I.G.d.G.), Complejo Hospitalario de Navarra; Brain Bank (T.T.), Navarrabiomed, Navarra Institute for Health Research (IdiSNA), Pamplona, Spain; Institute of Neurology (E.G.), Medical University of Vienna, Vienna, Austria; and Neurological Tissue Bank of the Hospital Clinic-IDIBAPS Biobank (E.G.), Barcelona, Spain. elena.erro.aguirre@cfnavarra.es.
Objective:
To describe the neuropathologic features and the molecular data of phosphorylated tau (pTau) in a new case of anti-IgLON5 disease.
Methods:
Review of clinical data, postmortem neuropathologic examination. Biochemical analyses of pTau were performed in brain samples from the present case and from a previously described patient with anti-IgLON5 with the characteristic brainstem tauopathy.
Results:
The patient was a 71-year-old man with a clinical syndrome consisting of sleep disturbance and bulbar symptoms. IgLON5 antibodies of predominant IgG4 subtype were detected in serum and CSF. He carried the HLA DRB1*10:01-DQB1*05:01 haplotype. Despite treatment with IV immunoglobulins, he unexpectedly died during sleep 2 years after disease onset. Histology showed neurofibrillary pathology and β-amyloid deposits consistent with Alzheimer disease (AD) of intermediate severity. pTau deposits were absent in the brainstem. There were few perivascular CD8+ T-cell infiltrates in the posterior hypothalamus, amygdala, and brainstem with microglial activation. The pTau immunoblot showed a pattern of bands consistent with AD, which was different from that observed in the patient with anti-IgLON5 with brainstem tauopathy who presented a differential band around 56 KDa.
Conclusion:
The absence of pTau deposits in the brainstem of the present patient suggests that the tauopathy of patients with anti-IgLON5 disease may be a late, secondary event. The anti-IgLON5 brainstem tauopathy has a specific molecular signature different from primary tauopathies. pTau deposits restricted to the hippocampus/limbic regions of patients with anti-IgLON5 may represent an age-related comorbidity.
