X-linked Lymphoproliferative Syndrome (Duncan Syndrome) By James Fernandez, MD, PhD, Cleveland Clinic Lerner College of Medicine at Case Western Reserve University Reviewed / Revised Jan 2023 View Patient Education Symptoms and Signs Diagnosis Treatment X-linked lymphoproliferative syndrome is an immunodeficiency disorder that results from a T-cell and natural killer cell defect and is characterized by an abnormal response to Epstein-Barr virus infection, leading to liver failure, immunodeficiency, lymphoma, fatal lymphoproliferative disease, or bone marrow aplasia.