Diagnostic value of aquaporin 4 antibody in assessing idiopathic inflammatory demyelinating central nervous system diseases in Egyptian patients.

Neuromyelitis optica immunoglobulin G (NMO-IgG) binds selectively to aquaporin 4 (AQP4). We aimed to evaluate the frequency of AQP4 antibody in Egyptian patients. We retrospectively evaluated 39 consecutive Egyptian patients with suspected idiopathic inflammatory demyelinating central nervous system disease (IIDCD) who visited the multiple sclerosis clinic at Kaser Al-Aini Hospital. The patients were diagnosed with NMO, other NMO spectrum disorders, or multiple sclerosis using the respective current diagnostic criteria. For the anti-AQP4 antibody assays, serum samples from all patients and 16 healthy matched controls were evaluated. The coded sera were tested for AQP4 antibody using an enzyme-linked immunosorbent assay kit. The relations between the clinical diagnosis and the AQP4 antibody serologic status were studied. Among the 39 patients, 21 (53.85%) were AQP4 antibody-positive. NMO spectrum disorders patients had a significantly higher level of AQP4 antibody compared with MS patients and controls (p<0.001). Only eight patients (36.36%) met the Wingerchuk 2006 criteria for NMO diagnosis excluding AQP4 antibody-seropositive status. AQP4 antibody was highly prevalent (almost 54%) in Egyptian IIDCD patients. Our research revealed that we must maintain a high index of suspicion for NMO spectrum disorders.