Congenital Dyserythropoietic Anaemia

CDA is a rare, inherited dyserythropoeitic anaemia characterised by ineffective erythropoiesis and intramedullary haemolysis. The inheritance is autosomal recessive. The fraction of haemoglobin F is often increased. CDA is classified into the following types based on bone marrow morphology:

• Type 1: occasional (3-7%) binucleate erythroblasts, inter-nuclear bridging
• Type 2: multi-nucleated late erythroblasts
• Type 3: gigatoblasts (erythroblasts with >=8 nuclei)

Complications

• Iron overload
• Gallstones and cholecystitis / cholangitis
• Hypersplenism – may necessitate splenectomy, may particularly benefit type 2 patients

Blood film features:

• Anisopoikilocytosis, often marked
• May have dimorphic picture
• Some macrocytes, most cells normocytic
• Teardrop cells
• Basophilic stippling
• nRBCs may be seen, especially after splenectomy (look for features of splenectomy)
• Other cell lines lack dyserythropoietic features

Differential diagnosis:

• Haemoglobin H disease (microcytic, hypochromic with polychromasia)
• Hereditary pyropoikilocytosis (microspherocytes, elliptocytes, red cells with bud-like projections and polychromasia)

Bone marrow features:

• Hypercellular marrow
• Erythroid hyperplasia with sometimes reversed myeloid:erythroid ratio
• Type 1 will have inter-nuclear bridging
• Type 2 and type 3 will have multinucleated erythroblasts