severe combined immunodeficiency disease
(seh-VEER kum-BIND IH-myoo-noh-deh-FIH-shun-see dih-ZEEZ)
A rare, inherited disease that is marked by a lack of B lymphocytes (white blood cells that make antibodies and help fight infections) and a lack of T lymphocytes (white blood cells that attack virus-infected cells, foreign cells, and cancer cells). Patients with this disease have a high risk of developing viral, bacterial, and fungal infections. Also called SCID.