MELAS syndrome complicated by anti-GFAP autoantibody positivity: a case report and literature review.

BACKGROUND: Autoimmune abnormalities have been reported in mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) syndrome, but anti-glial fibrillary acidic protein (GFAP) antibody positivity in both serum and cerebrospinal fluid (CSF) has not been previously described. We report such a case and review the literature on MELAS-associated autoimmune abnormalities. CASE PRESENTATION: A 46-year-old man presented with hearing loss, aphasia, and psychiatric symptoms. Brain magnetic resonance imaging (MRI) showed bilateral temporo-parietal lesions. Anti-GFAP antibodies were detected in both serum and CSF. Despite multiple immunotherapies including immunoglobulin, methylprednisolone, and cyclophosphamide, the patient showed minimal clinical improvement. Genetic testing revealed m.3243 A > G mutation (11.91% heteroplasmy), confirming MELAS syndrome. The patient died within three months of onset. CONCLUSIONS: To our knowledge, this is the first report of MELAS syndrome with concurrent serum and CSF anti-GFAP antibody positivity. This case expands the spectrum of autoimmune abnormalities observed in MELAS syndrome. Together with our literature review, this case suggests that mitochondrial dysfunction may trigger various secondary autoimmune responses. The clinical significance and pathogenic role of these autoantibodies in MELAS syndrome warrant further investigation.