Diamond Blackfan Anemia (DBA) Medical
Diamond Blackfan Anemia (DBA) is a rare genetic disease. It was first reported in 1936 and later described by two hematologists: Diamond and Blackfan in 1938. Most patients suffer from severe chronic anemia due to bone marrow failure. Most patients present shortly after birth with pallor, weakness, and growth failure. Many patients also have other medical problems such as short stature, thumb anomalies, and heart problems among others. Patients with DBA may also have slightly increased risk of developing cancer.
DBA can be diagnosed based on the medical and family history, physical examination, blood counts, level of the enzyme adenosine deaminase in the blood, and bone marrow test.
The disease is caused by mutation in one of several DBA genes. The two most common DBA genes are RPS19 and RPL5. The DBA genes are involved in production of protein in the cells. Genetic testing is now available for patients with DBA and can help to establish a diagnosis and identify the cause of the disease. As of August 2016, genetic testing can identify the mutated gene in about 70% of the patients. Two new non ribosomal genes have also now been identified - GATA 1 and TSR2.
Although a small proportion of the patients with DBA have mild disease, most patients have severe anemia and require treatment from birth with red blood cell transfusions about every 1 month. After approximately 15 episodes of transfusion, significant amount of iron from the transfusions can be accumulated in the body and the patients needs medications which facilitate excretion of iron. The common medication until recently was desferal which is injected under the skin over several hours almost daily. Recently an oral medication called exjade has become available.
Some patients respond to standard doses of prednisone followed by long-term maintenance with low doses. This treatment can eliminate the need for transfusions and has only few side effects. All patients receive such a trial; however, low dose prednisone is sufficient to prevent transfusions in only one third of the patients. Other treatments include metochlopromide and cyclosporine which are rarely effective. Bone marrow transplantation is the only curative therapy for anemia in DBA; however, due to serious potential short-term and long-term side effects of this therapy, it is rarely used in DBA.
Patients and families face major challenge before and after the diagnosis is made. Substantial progress has been made in understanding the clinical features of DBA, the genetic background, how the disease develops and treatment. However, the following challenges still exist:
Establishing effective tools to establish a diagnosis and discriminate DBA from other inherited bone marrow failures such as congenital dyserythropoietic anemia and Shwachman-Diamond syndrome. Identifying the full spectrum of the DBA genes is critical step.
Determining why some patients develop very severe disease and need life-long treatment with transfusions, while others respond to low doses of prednisone or enter into prolonged complete remission.
Understanding how the DBA genes work and why mutations in the genes cause the disease.
Developing effective treatment to treat the anemia in case prednisone does not work; an oral iron cheletor with less side effects and which is suitable for patients of all ages; effective therapies for other problems that patients with DBA may have such as growth failure and feeding difficulties.
Yigal Dror MD, FRCP(C)
Associate Professor of Paediatrics,
Division of Hematology/Oncology,
Director, Marrow Failure and Myelodysplasia Program,
Scientist, Program in Cell Biology, Research Institute,
The Hospital for Sick Children, The University of Toronto
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