Ribosomal proteins S3a, S13, S16, and S24 are not mutated in patients with Diamond-Blackfan anemia

Considerable effort has been invested in identification of a gene responsible for Diamond-Blackfan anemia (DBA). The disorder is characterized by red cell hypoplasia presenting in early infancy and is accompanied in about 40% of the patients by various physical anomalies (for review see Willig et al1). Ribosomal protein S19 (RPS19) was identified as a candidate gene for DBA and mutations in this gene have been described in 25% of DBA patients.2,3 However, the mechanism by which mutations in RPS19 can lead to DBA remains unclear.

RPS19 is a structural component of a small ribosomal subunit and is known to have two other functions. First, RPS19 homodimers are released by apoptotic cells and act as a chemotactic factor for monocytes during macrophage-dependent apoptotic cell clearance.4 Second, RPS19, together with ribosomal proteins S3a, S13, S16, and S24, participates in the binding of eukaryotic initiation factor 2 (eIF-2) to ribosomes.5 eIF-2 plays a central role in the initiation of translation, and its function is controlled in an erythroid-specific manner by heme-regulated kinase.6 To investigate the possibility that DBA phenotype might result from mutations in ribosomal proteins involved in eIF-2 binding, we sequenced cDNAs for RPS3a, S13, S16, and S24 in 14 patients from the Czech National DBA Registry. Five of these patients have been previously shown to carry a mutation in the RPS19 gene.7 

After obtaining informed consent, total RNA was isolated from peripheral blood mononuclear cells, and reverse transcription was performed using an oligo(dT) primer. Primers specific for full-length coding regions of RPS3a, S13, S16, and S24 were used for PCR amplification. PCR products were sequenced on an automated genetic analyzer, and resulting sequences were evaluated for the presence of mutations.

In all DBA patients tested, no mutations in RPS3a, S13, S16, and S24 were found on the cDNA level. We therefore conclude that these four of the five ribosomal proteins important for eIF-2 binding to ribosomes are not involved in DBA pathogenesis.

Supported by the Czech Ministry of Health grant CEZMZ 0023736001.