RESUMEN
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). DESIGN AND METHODS: We performed fluorescence in situ hybridization of 5q31 in 716 patients, divided into two groups: group A patients (n=637) in whom the 5q deletion had not been detected at diagnosis by conventional banding cytogenetics and group B patients (n=79), in whom cytogenetic analysis had revealed the 5q deletion (positive control group). RESULTS: In group A (n=637), the 5q deletion was detected by fluorescence in situ hybridization in 38 cases (5.96%). The majority of positive cases were diagnosed as having the 5q- syndrome. The deletion was mainly observed in cases in which the cytogenetics study had shown no metaphases or an aberrant karyotype with chromosome 5 involved. In group B (n=79), the 5q deletion had been observed by cytogenetics and was confirmed to be present in all cases by fluorescence in situ hybridization of 5q31. CONCLUSIONS: Fluorescence in situ hybridization of 5q31 detected the 5q deletion in 6% of cases without clear evidence of del(5q) by conventional banding cytogenetics. We suggest that fluorescence in situ hybridization of 5q31 should be performed in cases of a suspected '5q- syndrome' and/or if the cytogenetic study shows no metaphases or an aberrant karyotype with chromosome 5 involved (no 5q- chromosome).
Asunto(s)
Deleción Cromosómica , Cromosomas Humanos Par 5/genética , Síndromes Mielodisplásicos/genética , Estudios de Casos y Controles , Aberraciones Cromosómicas , Citogenética/métodos , Femenino , Eliminación de Gen , Hematología/métodos , Humanos , Hibridación Genética , Hibridación Fluorescente in Situ , Cariotipificación , Masculino , Metafase , Síndromes Mielodisplásicos/diagnósticoRESUMEN
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.