Serum Level of Anti-Tubulin-Alpha-1c Antibody in Behçet Disease and Its Relation to Disease Activity and Severity Eman Eldessoki Elshahawy 1 Yasmeen Mohamed Abass Eltayeb 2 Asmaa Ahmed Saad Hassan 3 Youmna Ahmed Ahmed Amer 4 1 Professor of Rheumatology Department, Faculty of Medicine, Zagazig University, Egypt 2 Department of Rheumatology, Faculty of Medicine, Zagazig University, Egypt 3 Lecturer of Clinical Pathology Department, Faculty of Medicine, Zagazig University, Egypt 4 Assistant Professor of Rheumatology, Rehabilitation and Physical Medicine Department, Faculty of Medicine, Zagazig University, Egypt Abstract Behçet's Disease (BD) is a chronic, multisystem inflammatory condition with unpredictable activity and diverse clinical manifestations. Reliable biomarkers for monitoring disease severity and activity are still needed. This study aimed to evaluate serum anti-tubulin-alpha-1c antibody levels and their association with clinical features, disease activity and severity of BD. Methods: This case-control study included 84 participants: 42 BD patients from the Rheumatology and Rehabilitation Department, Zagazig University Hospitals, and 42 healthy controls. Serum anti-tubulin-alpha-1c antibody levels were measured using ELISA. Results: Serum anti-tubulin-alpha-1c levels were significantly higher in patients with arthritis (P=0.01), anterior uveitis (P=0.03), panuveitis (P=0.02), optic atrophy (P<0.001), skin lesions (P=0.01), vascular involvement (P=0.043), stroke (P=0.048), and psychosis (P=0.04). A positive significant correlation was observed between antibody levels and both the Behçet’s Disease Damage Index (r=0.652, P<0.001) and the Birmingham Vasculitis Activity Score (r=0.361, P=0.02). Antibody levels were significantly higher in active compared to inactive disease (P=0.04). ROC analysis showed good diagnostic accuracy of anti-tubulin-alpha-1c in distinguishing active from inactive disease (AUC=0.731), detecting vascular lesions (AUC=0.694), and identifying high disease severity (AUC=0.824). Conclusion: Serum anti-tubulin-alpha-1c antibody levels are significantly associated with disease activity, severity, and multiple clinical features of BD. These findings suggest that it may serve as a valuable biomarker for monitoring disease activity and identifying patients at higher risk for severe or multisystem involvement. Keywords :Behçet' s disease, anti-tubulin-alpha-1c, disease activity, ELISA