The recognition of a patient with DBA who subsequently developed CVID lends support to our previous finding of a heterozygous mutation in the SBDS gene of SBDS in another CVID patient, suggesting that ribosome biogenesis defects are responsible for a subset of CVID. Genetic defects in the ribosomal translational machinery responsible for various bone marrow failure syndromes are recognized readily when they manifest in children, but diagnosing these in adults presenting with complex phenotypes and hypogammaglobulinaemia can be a challenge. In this perspective paper, we discuss our clinical experience in CVID patients with ribosomopathies, and

review the immunological abnormalities GSI-IX in other conditions associated with ribosomal

dysfunction. With genetic testing available for various bone marrow failure syndromes, our hypothesis that ribosomal abnormalities may be present in patients with CVID could be proved in future studies by testing for mutations in specific ribosomal genes. New knowledge might then be translated into novel therapeutic strategies for patients in this group of immunodeficiency disorders. Common variable immunodeficiency disorders (CVID) comprise a range of hypogammaglobulinaemias, for which a small number of genetic defects have been identified [1–3]. However, these account for only a small proportion of cases of CVID, and the majority of patients have no identified genetic cause. A number of bone marrow failure syndromes are now recognized to be due to defects in ribosome biogenesis with mutations in genes coding for ribosomal proteins. Various immunological abnormalities find more are evident in these syndromes and old provide proof that failure of optimal ribosome function, ‘ribosomopathies’, can also affect cells of the immune system. These syndromes are heterogeneous in their clinical presentations: for example, patients with Shwachman–Diamond syndrome (SDS) with confirmed mutations in the SBDS gene (Chr7q11) may not have all the characteristic features of neutropenia, skeletal defects and pancreatic insufficiency [4]. There is emerging evidence

that loss of Shwachman–Bodian–Diamond syndrome (SBDS) protein affects haematopoeisis and numbers of circulating B lymphocytes [5]. Craniofacial malformation syndromes such as Treacher–Collins syndrome, caused by haploinsufficiency of the treacle protein, also affect the cells of the immune system [6], and a broader immunological defect has been described in the congenital anaemia of Diamond–Blackfan syndrome (Diamond–Blackfan anaemia: DBA) [7]. The 5q- syndrome, a somatically acquired deletion of chromosome 5q and a subtype of myelodysplastic syndrome, leads to haploinsufficiency of a ribosomal protein that is also implicated in DBA. The active eukaryotic ribosome, the site of protein synthesis, is composed of 40S and 60S subunits.