What is DBA?

Diamond Blackfan Anemia (DBA) is a blood condition, present at birth, which is characterized by a failure of the bone marrow to produce red blood cells, other blood cells such as white cells and platelets are usually not affected. By itself, the term “anemia” means low red cell counts. Unlike other types of anemia, DBA is a bone marrow failure syndrome. It has also been linked to a genetic mutation in some individuals. Severe anemia is frequently found at birth and the majority of individuals are diagnosed before their first birthday.

Where does the name come from?

Diamond Blackfan Anemia’s name originated from the founder of the Hematology/Oncology branch at Children’s Hospital in Boston Louis K. Diamond M.D. and Chief of the Pediatric Department Kenneth D. Blackfan.

What causes it?

DBA occurs when the bone marrow fails to make adequate numbers of red blood cells. Scientists are currently studying the genes involved in DBA to see why it occurs. RPS-19 has been linked in 25% of DBA cases but not having this gene does not mean you do not have DBA. Forty percent of the patients with DBA have a mutation in a gene or genes located in a wide region in the short arm of chromosome 8 (8p22.3-23) but a candidate gene has not been identified yet. There has been no success in pinpointing the genetic defect in the DBA patients who have neither RPS-19 mutation nor chromosome 8p22.3-23 mutation.

According to the DBA Registry of America: DBA can be either congenital (such as DBA) or acquired (such as TEC, infection associated, malignancy associated, from drugs/toxins, etc.).

Diagnosis?

In addition to a complete history and physical examination, other diagnostic tests are used to aid in the diagnosis of DBA. Initially, blood work is performed to evaluate the degree of anemia and examine other body systems. One particular blood test called the red cell ADA (adenosine deaminase) is usually present at elevated levels in patients with DBA. In addition to blood tests, samples of bone marrow (Bone Marrow Aspirate and Biopsy) are taken to examine all of the blood cell lines (red cells, white cells, and platelets), genetic make up of the bone marrow, and the physical architecture of the bone marrow. 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 fetal hemoglobin (Hb F) than normal, all which can be tested through bloods and bone marrow biopsies. 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. According to the Diamond Blackfan Anemia Registry of North America: The diagnostic criteria for DBA are: age less than 1 year, moderate to severe macrocytic anemia, reticulocytopenia (low retic count), normal bone marrow cellularity with a paucity of erythroid precursors.

Major criteria that support a DBA diagnosis are: the RPS19 mutation or a positive family history. Minor supportive criteria are: elevated erythrocyte adenosine deaminase (eADA) activity (normal ADA is 0.20-0.98, in DBA you see 0.45-5.11), congenital anomalies, elevated fetal hemoglobin, no evidence of another type of bone marrow failure. [My notes say that you should have all the diagnostic criteria and a couple of the supporting criteria to have classical DBA.]

A comparison of DBA and TEC (transient erythroblastopenia of childhood): DBA is inherited, TEC is aquired. 50% of DBA patients show some physical anomaly [she's including short stature here], no TEC patients do. There are also some CBC count differences, but the main ones would be that DBA his increased eADA while TEC doesn’t, DBA has increase mean corpuscle volume (MCV – the size of the red blood cell), and generally TEC has no increase in fetal hemoglobin except during recovery.

What is a normal hemoglobin level?

On average, normal hemoglobin levels range from 12 to 18 g/dL (grams per deciliter) of blood for both sexes. For men, a normal hemoglobin count is between 14 and 18 g/dL; for women, the normal range is between 12 and 16g/dL. For children 12 to 16 g/dl.