Fluorescence in situ hybridization improves the detection of 5q31 deletion in myelodysplastic syndromes without cytogenetic evidence of 5q-.

Background: More than 50% of patients with myelodysplastic syndromes present cytogenetic aberrations at diagnosis. Partial or complete deletion of the long arm of chromosome 5 is the most frequent abnormality. The aim of this study was to apply fluorescence in situ hybridization of 5q31 in patients diagnosed with de novo myelodysplastic syndromes in whom conventional banding cytogenetics study had shown a normal karyotype, absence of metaphases or an abnormal karyotype without evidence of del(5q).

Deletion of sequences flanking the t(9;22) breakpoint: a secondary genetic event associated with loss of cytogenetic response to interferon in a Philadelphia-positive chronic myeloid leukaemia patient.

We present a Ph-positive chronic myeloid leukaemia patient who lost a complete cytogenetic response (CCR) of 23 months duration at the time of detection of a deletion, not previously observed, of chromosomes 9 and 22 sequences flanking the translocation breakpoint on the derivate 9 chromosome. To our knowledge, this is the first case in which a deletion at the t(9;22) breakpoint has arisen as a secondary genetic alteration produced after formation of the t(9;22) translocation. It remains to be determined whether this genetic abnormality has the same prognostic importance as when observed at diagnosis.