Congenital dyserythropoietic anemia type I with bone abnormalities, mutations of the CDAN I gene, and significant responsiveness to alpha-interferon therapy.

Congenital dyserythropoietic anemia type I (CDA I) is a rare autosomal recessive disorder with ineffective erythropoiesis, characteristic morphological abnormalities of erythroblasts, and iron overloading. CDA I is caused by mutations in the CDAN I gene, encoding a protein named codanin-1. Complex bone abnormalities, especially syndactyly, have not been systematically described with this disease. We present two cases of morphologically and genetically confirmed CDA I with striking bone abnormalities and response to treatment with alpha-interferon. Our cases clearly document the association of skeletal anomalism with CDA I and indicate that codanin-1 may play a role in the development of the skeleton.