In a study published in 2007, the transcriptome of bone marrow CD34+ cells was investigated in a cohort of ten patients with the 5q- syndrome using microarray-based gene expression profiling.12 Several candidate genes mapping to the CDR of the 5q- syndrome showed haploinsufficiency in 5q- syndrome patients, including RPS14, encoding a component of the 40S ribosomal subunit, and CSNK1A1, encoding a serine/threonine kinase.12 Crucially, these two genes would be shown in subsequent studies14,15 to have an important role in the molecular pathogenesis of the 5q- syndrome. Here, CSNK1A1 is linked to myelodysplastic syndrome associated with isolated del(5q).