For the rare leukodystrophies, where treatment options have historically been confined to symptom management, any credible pathway toward disease modification represents a meaningful shift. Alexander disease — caused by dominant mutations in the gene encoding Glial Fibrillary Acidic Protein (GFAP) — has long exemplified this therapeutic void, but a convergence of biomarker research and gene-silencing technology is beginning to change that picture.
This clinical review consolidates current understanding of Alexander disease across its full phenotypic range, from neonatal presentations with severe developmental arrest to adult-onset forms characterized by bulbar dysfunction, ataxia, and progressive spinal cord degeneration. Over 100 distinct GFAP mutations have now been catalogued, yet meaningful genotype-phenotype correlations remain frustratingly elusive — a diagnostic obstacle compounded by overlap with other neurological conditions. The pathogenic mechanism centers on mutant GFAP protein aggregation, oxidative stress, and cytoskeletal disruption within astrocytes, ultimately producing the hallmark Rosenthal fiber inclusions. Characteristic MRI patterns, combined with molecular confirmation, anchor diagnosis. Elevated cerebrospinal fluid GFAP levels are emerging as a potential disease-activity biomarker, though their clinical sensitivity and specificity remain under investigation. Among the most closely watched therapeutic candidates are antisense oligonucleotides — particularly zilganersen — and AAV-mediated gene silencing strategies designed to reduce toxic GFAP expression.
Alexander disease illustrates the broader challenge facing astrocytopathies: even when a single causal gene is identified, translating that knowledge into therapeutics takes decades. The antisense oligonucleotide approach used here mirrors advances in spinal muscular atrophy and transthyretin amyloidosis, where RNA-level interventions have transformed prognosis. That said, this is a narrative review — not a meta-analysis or trial data — so clinical translation timelines remain speculative. With an estimated prevalence well under one in a million, powering definitive trials is extraordinarily difficult. The review is nevertheless valuable as a comprehensive clinical reference, particularly for neurologists encountering adult-onset presentations, which are frequently misdiagnosed. The emphasis on CSF GFAP as a monitoring tool is an incremental but practically useful addition to the diagnostic toolkit.