What is DBA ?

Diamond Blackfan Anæmia (DBA) is a form of anæmia where the bone marrow produces little or no red blood cells (which transport oxygen throughout the body), resulting in severe deterioration of normal life-sustaining functions. The condition is extremely rare, affecting only 600 - 700 children and adults worldwide. The condition requires intensive therapy, and has no known cure, although bone marrow transplants can be curative.

What causes DBA ?

Little is known about the condition because it is so rare. Research has shown a possible genetic link, as DBA can be passed from parents to children. In many cases, it occurs sporadically. In a third of cases there are related physical defects, including thumb, kidney and facial abnormalities, but in others there are no physical signs that the sufferer has DBA. DBA also has a range of symptoms, to those needing little or no treatment, through those whose bone marrow can produce red cells through steriod therapy to those dependent on transfusions.

How is DBA diagnosed ?

DBA presents within the first two years of life, and in some cases is diagnosed at or before birth. Because of the rarity of the condition, diagnosis can sometimes take months; in other cases it can be diagnosed immediately.

Usually, initial bloods are taken to test for low hæmoglobin and high ADA (adenosine deaminase activity) in the blood. This is not definitive, but points to DBA as a likely cause. Bone marrow biopsies can confirm that the erythroid ( red cell ) precursors are depleted, which can point to viral infection ( Parvovirus B19 ) or DBA.

DBA sufferers usually have a very high MCV (Mean Cell Volume) so tend to have larger red blood cells, and a higher percentage of fœtal hæmoglobin (Hb F) than normal, all which can be tested through bloods and bone marrow biopsies.

Bone marrow biopsies involve taking a small amount of marrow from the hip or thigh bone, usually under general anæsthetic in small children. A large needle is inserted into the bone and the marrow is aspired. It is a short and relatively painless operation.

Doctors may also check the reticulocyte count. High reticulocyte counts point to conditions where blood is being created normally but is being destroyed. Low counts indicate a lack of red cell production. In DBA, reticulocyte counts are very low, and can be zero.

What are the symptoms of DBA ?

DBA has symptoms in common with all types of anæmia. Pallor ( paleness, easy to check by looking at the palms of the hand, inside the eyelid, and in the mouth), tachycardia ( irregular heartbeat) and heart murmurs due to the increase in work the heart needs to do to keep oxygen moving around the body . This can lead to irritability, tiredness, and fainting.

Since DBA is diagnosed at a very early age, it is difficult for children to tell their parents how they are feeling. Parents usually notice that 'something is wrong' well before diagnosis.

What Treatments are available ?

Treatment currently consists of two main therapies : steriod therapy and regular transfusions.

Around 70% of DBA-diagnosed patients respond initially to prednisone therapy, although response has been known to fail spontaneously. Almost all of those that do respond must continue to take steroids for the rest of their lives. Side-effects can include stunting of growth, water retention, bone weakening, diabetes, reduced immunity, glaucoma, cataracts and high blood pressure.

Those that do not respond to steroids, or need too high a dosage to sustain red cell count, require regular transfusions. The body normally recycles iron, storing it in the liver, heart and pancreas for reuse. DBA sufferers also store recycled iron, but as it is never reused it can lead to a build up of iron in the body, causing a poisoning of the system which requires regular chelation therapy to reduce the amount of iron. Iron retention can lead to heart and liver problems, as well as diabetes and growth problems.

A bone marrow transplant can lead to normal red cell production, but this is a very risky alternative. Matching bone marrow donors are hard to find, and if the procedure fails, the patient may die.

Is there any research into finding a cure for DBA ?

Research into the cause of DBA and other related bone marrow failures is being carried out at several centres internationally. Indirectly, it may lead to better understanding of the condition, and in turn better treatments or cures.

Pharmaceutical research is practically non-existent, due to the small number of DBA sufferers worldwide. However, pharmaceutical research into related conditions may lead to better treatment for DBA patients, especially related to transfusions and chelation therapy.