Diamond-Blackfan Anaemia and Transient Erythroblastopenia
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Direct answer
Diamond-Blackfan anaemia is a congenital pure red cell aplasia that presents in infancy with macrocytic anaemia, reticulocytopenia and normal white cell and platelet counts. Most cases arise from a ribosomal protein gene defect, and most respond to corticosteroids. Transient erythroblastopenia of childhood looks similar in a toddler but is acquired, normocytic and self-limiting, so it needs supportive care rather than steroids.
What you must remember
- Presentation: pallor and poor weight gain appear in the first year, usually within the first few months, with reticulocytopenia and a normal white cell and platelet count.
- Marrow finding: erythroid precursors are absent or sharply reduced while myeloid and megakaryocytic lines are preserved, which defines a pure red cell aplasia.
- Indices and HbF: the anaemia is typically macrocytic and fetal haemoglobin is raised, a pattern that helps separate it from acquired causes.
- Erythrocyte ADA: red cell adenosine deaminase is classically raised in this disease and normal in transient erythroblastopenia, which supports the diagnosis.
- Genetics: RPS19 is the commonest mutated gene, followed by other ribosomal protein genes such as RPL5 and RPL11, and many cases are sporadic.
- Physical anomalies: cleft palate, micrognathia, triphalangeal thumb and cardiac or renal defects occur in a substantial minority of patients.
- Treatment: corticosteroids are first-line, transfusion and iron chelation support non-responders, and haematopoietic stem cell transplantation offers a potential cure.
- Cancer risk: patients carry an increased risk of myelodysplasia and some solid tumours, so long-term follow-up is needed.
Where the exam tries to catch you
Both conditions present as isolated red cell failure, so the traps depend on which features the candidate overlooks.
- Trap: giving steroids to every infant with pure red cell aplasia. Correct: transient erythroblastopenia recovers without treatment, so steroids are reserved for confirmed Diamond-Blackfan anaemia with persistent erythroid failure.
- Trap: assuming normal white cell and platelet counts exclude Diamond-Blackfan anaemia. Correct: normal other lineages are the expected pattern, because the defect is confined to the red cell line.
- Trap: attributing macrocytosis and a raised ADA to viral marrow suppression. Correct: these findings point to an intrinsic ribosomal defect, not a transient infective cause.
Examine the thumbs and face and ask about family history before labelling the child.
Frequently asked questions
Which marrow finding defines Diamond-Blackfan anaemia?
Diamond-Blackfan anaemia is defined by pure red cell aplasia on bone marrow examination, meaning erythroid precursors are absent or sharply reduced. Myeloid and megakaryocytic lineages are preserved, so white cell and platelet counts usually stay normal.
Which gene is most often mutated in Diamond-Blackfan anaemia?
RPS19 is the commonest mutated gene in Diamond-Blackfan anaemia and encodes a ribosomal protein. Mutations in other ribosomal protein genes, such as RPL5 and RPL11, account for a substantial share of the remaining cases.
How does transient erythroblastopenia of childhood differ from Diamond-Blackfan anaemia?
Transient erythroblastopenia of childhood is an acquired, self-limiting red cell aplasia that usually affects children aged six months to four years, peaking at one to three years. It is normocytic, has normal erythrocyte adenosine deaminase, and recovers spontaneously without steroid therapy.
Why is erythrocyte adenosine deaminase useful in Diamond-Blackfan anaemia?
Erythrocyte adenosine deaminase activity is raised in most children with Diamond-Blackfan anaemia, so a raised value supports the congenital diagnosis. It is normal in transient erythroblastopenia, and genetic testing remains the confirmatory step.
What is the first-line treatment for Diamond-Blackfan anaemia?
Corticosteroids, usually prednisolone, are the first-line treatment, and most children respond although the dose is tapered once counts improve. Children who do not respond rely on regular transfusion and iron chelation, and haematopoietic stem cell transplantation offers a potential cure.