Prognostic value of auto-antibodies to extractable nuclear antigens in neuromyelitis optica

Background: Compared with the Western population, central demyelinating disorders are relatively rare while the data on the prognostic value of autoantibodies together with clinical characteristics and cognitive dysfunction has rarely been explored in neuromyelitis optica (NMO) and multiple sclerosis (MS). Methods: Nineteen patients with MS and 14 with NMO underwent clinical profiling and cognitive assessment. According to serology tests, they are divided into four subgroups for further analysis. Results: There was higher frequency of aquaporin-4 immunoglobulin G. sero-positivity (64.3% vs. 10.5%; p=0.003) and antinuclear antibodies (ANA) and/or antibodies to extractable nuclear antigens (anti-ENA) in NMO compared to MS (42.9% vs. 5.2%; p=0.026). The presence of anti-ENA represented a unique clinical phenotype, with longer segment of myelitis (p=0.049), female preponderance, and an inverse correlation between age-of-onset and annual relapse rate (rho= -0.88, p=0.021). Among patients with anti-ENA positivity, comprehensive serology panels revealed Sjogren's syndrome A antibodies as the most common (83%), in contrast to limited clinical documentation of Sjogren's syndrome (16%). There was no significant difference in cognitive assessment by anti-ENA status. MS and NMO represent two different serologic entities. Conclusions: Anti-ENA may have prognostic value for its linkage to a unique clinical phenotype, which has longer initial segment of myelitis, female preponderance, and higher annual relapse rate on earlier age-of-onset, but has limited clinical impact on cognition. Further studies are warranted to investigate whether anti-ENA represents an epiphenomenon of myelitis or simply a systemic inflammatory state.