Deletions of PURA, at 5q31, and PURB, at 7p13, in myelodysplastic syndrome and progression to acute myelogenous leukemia

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Abstract
Deletions or monosomy of chromosomes 5 and 7 are frequently observed in myelodysplastic syndromes (MDS) and acute myelogenous leukemia (AML). In this study two genes, PURA and PURB, encoding functionally cooperative proteins in the Pur family, are localized to chromosome bands 5q31.1 and 7p13, respectively. One or both of these loci are shown to be hemizygously deleted in 60 MDS or AML patients using fluorescence in situ hybridization (FISH). High-resolution mapping of PURA localizes it approximately 1.1 Mb telomeric to the EGR-1 gene. Frequency of PURA deletion and segregation with EGR-1 indicate that PURA is within the most commonly deleted segment in myeloid disorders characterized by del(5)(q31). No mutations have been detected within the coding sequence of PURA. Concurrent deletions of PURA and PURB occur in mds at a rate nearly 1.5-fold higher than statistically expected and in aml at a rate >5-fold higher. This novel simultaneous deletion of two closely related gene family members may thus have consequences related to progression to AML. Purα, an Rb-binding protein, has been implicated in cell cycle control and differentiation, and Purα and Purβ are reported to function as heterodimers. Alterations in these genes could affect a delicate balance critical in myeloid development.