Neuromyelitis optica spectrum disorders (NMOSD) are severe inflammatory autoimmune conditions of the central nervous system (CNS) . The discovery of NMOSD-specific aquaporin 4 (AQP4) antibody has established that NMOSD is indeed a distinct entity . Approximately 80% of patients with NMOSD test positive for aquaporin-4 (AQP4) immunoglobulin G (IgG) antibodies .AQP4-IgG associated NMOSD appears to target astrocytes, not myelin, leading to elevated markers of astrocyte injury during attacks . Untill now there is limited research about understanding the biomarkers of astrocyte injury and the following reactive gliosis. Family with sequence similarity 19-memberA5 (FAM19A5) protein is postulated to regulate nervous and immune cells of the brain as a brain-specific chemokine, but its precise functional role is not well understood . A recent study suggested that FAM19A5 is secreted by reactive astrocytes following CNS damage and triggers reactive gliosis . In another recent study, serum FAM19A5 was higher in patients with NMOSD-AQP4 than in other CNS demyelinating diseases and healthy controls . So, we need to study the level of this novel biomarker among our Egyptian NMOSD patients and whether it shall be a new biomarker for NMOSD .

Moreover just few studies conducted on cognitive dysfunctions in NMOSD patients and they demonstrate a significant decrease of cognitive abilities and the prevalence of CI in different samples varies between 30 and 70% .So further studies are needed to investigate the cognitive performance in NMOSD patients

Sixty patients diagnosed as NMOSD based on the recently revised 2015 international consensus diagnostic criteria for NMOSD ,attending Neurology clinic, Asyut University hospitals, Asyut university and Kasr Al-Ainy multiple sclerosis/neuroimmunology clinic, Cairo University hospitals, Cairo University, Egypt, through one and half year from study onset. Sixty healthy volunteers, without any neurological or systemic medical diseases, age and sex matched , will be enrolled as healthy controls(HCs).

Aim of the work :

1. Determining the serum level of FAM19A5 in a cohort of Egyptian patients with NMOSD in comparison with healthy controls and its relationship with the different clinical phenotypes and parameters and disease severity of NMOSD patients.
2. Cognitive performance of NMOSD patients in comparison with healthy controls.

Inclusion Criteria:

• 1-Both NMOSD AQP-4 +ve and AQP-4 -ve. 2-Age <18 and >60 years. 3-Both males and females. 4-Both receiving or not receiving current immunosuppressants. 5-Any score of extended disability status scale (EDSS).

Exclusion Criteria:

• 1-Any neuropsychiatric disorder other than NMOSD such as multiple sclerosis ,CNS infectious diseases or malignancy.

  2-Systemic conditions influencing analysis of clinical and serological data , such as general infection, malignancy, and hematologic diseases.

  3-Illiterate patients. 4-History of drug or alcohol abuse

Sixty patients diagnosed as NMOSD based on the recently revised 2015 international consensus diagnostic criteria for NMOSD ,attending Neurology clinic, Asyut University hospitals, Asyut university and Kasr Al-Ainy multiple sclerosis/neuroimmunology clinic, Cairo University hospitals, Cairo University, Egypt, through one and half year from study onset. Sixty healthy volunteers, without any neurological or systemic medical diseases, age and sex matched , will be enrolled as healthy controls(HCs).