Diamond-Blackfan anemia is a rare inherited bone marrow failure syndrome (five 
to seven cases per million live births) characterized by an aregenerative, 
usually macrocytic anemia with an absence or less than 5% of erythroid 
precursors (erythroblastopenia) in an otherwise normal bone marrow. The platelet 
and the white cell counts are usually normal but neutropenia, thrombopenia or 
thrombocytosis have been noted at diagnosis. In 40 to 50% of DBA patients, 
congenital abnormalities mostly in the cephalic area and in thumbs and upper 
limbs have been described. Recent analysis did show a phenotype/genotype 
correlation. Congenital erythroblastopenia of DBA is the first human disease 
identified to result from defects in ribosomal biogenesis. The first ribosomal 
gene involved in DBA, ribosomal protein (RP) gene S19 (RPS19 gene), was 
identified in 1999. Subsequently, mutations in 12 other RP genes out of a total 
of 78 RP genes have been identified in DBA. All RP gene mutations described to 
date are heterozygous and dominant inheritance has been documented in 40 to 45% 
of affected individuals. As RP mutations are yet to be identified in 
approximately 50% of DBA cases, it is likely that other yet to be identified 
genes involved in ribosomal biogenesis or other pathways may be responsible for 
DBA phenotype.