5q- Myelodysplastic Syndrome Masquerading as Diamond Blackfan Anemia

Diamond Blackfan anemia is a congenital bone marrow failure syndrome characterized by hypoproliferative anemia, often with associated physical abnormalities. Perturbations of the ribosome appear critically important to the development of DBA, as alterations in 9 different ribosomal protein genes have been identified in multiple unrelated families, along with rarer abnormalities of additional ribosomal proteins. However, presently only 50-60% of patients have an identifiable genetic lesion by ribosomal protein gene sequencing. Using genome-wide SNP array to evaluate for regions of recurrent copy variation, we identified 2 patients with mosaic loss in the region of the the chromosome 5-deleted region involved in somatically-acquired 5q- myelodysplastic syndrome. Samples were analyzed on Illumina HumanOmni1_Quad, HumanOmniExpress, or HumanOmniExpressExome Genotyping bead arrays; 1 patient was available for longitudinal study including assessment of mosaicism in lymphoid and myeloid-enriched cell populations before treatement with lenolidamide. Similar studies were performed while on lenoldamide therapy in peripheral blood at 3 months and in bone marrow at 20 months of treatment. One patient with mosaic deletion of 5q was available for longitudinal study including assessment of gene expression in bone marrow before and during treatment with lenalidomide.