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INTRODUCTION

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  • Congenital dyserythropoietic anemias (CDA) are a heterogeneous group of disorders characterized by anemia, the presence of multinuclear erythroid precursors in the marrow, ineffective erythropoiesis, and iron overload.

  • Although rare, uncovering the molecular basis of CDA has helped unravel novel aspects of the cell biology of erythropoiesis.

  • Three types of CDA have been distinguished. In addition, a number of patients with forms of congenital dyserythropoietic anemia that do not fit these categories have been described.

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CDA TYPE I

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Clinical and Laboratory Features

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  • Presents in infancy or adolescence.

  • Autosomal recessive inheritance, caused by mutations of the CDAN1 gene (codanin-1), encoding a cell-cycle-regulated protein of yet unknown function; homozygosity is often associated with consanguinity. In a number of patients, only one CDAN1 allele is identified with a mutation; other causative genes suspected because in rare CDA I families, no mutations of the CDAN1 gene found.

  • Moderately severe macrocytic anemia (approximately 9.0 g/dL).

  • Hepatomegaly and cholelithiasis are common.

  • Splenomegaly increases with age.

  • Specific morphologic findings of CDA type I are summarized in Table 7–1 and exemplified in Fig. 7–1.

  • Dysmorphologic features may be present, the most common involve the bones of the hand and the foot. Other, less common features are small stature, almond-shaped blue eyes, hypertelorism (increased distance between two body parts or organs), and micrognathism.

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Table Graphic Jump Location
TABLE 7–1MAIN FEATURES OF TYPES I, II, AND III CONGENITAL DYSERYTHROPOIETIC ANEMIAS
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FIGURE 7–1

Light microscopy of marrow. A. Congenital dyserythropietic anemia type I. Note the intranuclear chromatin bridge marked by an arrow. This bridge is unusually long. B. Congenital dyserythropietic anemia type II. The two arrows point to binucleate erythroblasts, characteristic of this type. (Used with permission from Dr. Odile Fenneteau.)

(Source: Williams Hematology, 8th ed, Chap. 39, Fig. 39–2, p. 515.)

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