Diamond Blackfan Anemia (DBA) is a rare, congenital anemia characterized by a paucity of erythroid progenitor cells in the bone marrow, reticulocytopenia, and an increased size (macrocytosis) of the remaining circulating red blood cells (RBCs), with elevated adenosine deaminase activity and increased fetal hemoglobin. The gene discussed is ADA; the disease is Diamond-Blackfan anemia.