Molecular analysis of six variant Philadelphia chromosome translocations in chronic myeloid leukemia

Mario Sessarego, Giovanni Martinelli, Andrea Chiamenti, Raffaella Defferrari, Giuseppina Fugazza, Roberto Bruzzone, Franco Ajmar, Pier Franco Pignatti

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In 420 Philadelphia positive (Ph+) chronic myeloid leukemia (CML) patients karyotyped at diagnosis in our laboratory, 26 Ph variants (6.2%) were observed. Twelve of them are reported. Five cases are "simple" variants without detectable involvement of band 9q34, and seven are "complex," since a third chromosomal band is involved in the Ph formation. Two translocations [t(7;22)(q36;q11) and t(9;22;12)(q34;q11;q11)] are reported for the first time. Six cases were characterized molecularly, and bcr-abl rearrangement was demonstrated, confirming involvement of 9q34 band also in the cases in which chromosomes 9 appear cytogenically normal. Chimeric mRNAs in which M-BCR exon 3 is joined to abl exon 2 (type b3-a2) were detected in four of six cases; one case showed a DNA breakpoint in zone III, which may also give rise to the same transcript. In one case, mRNA junction was b2-a2. The frequency of the b3-a2 junction occurs more frequently in CML patients with a Ph variant than in patients with the standard translocation, suggesting a preferential correlation between this type of transcript and the involvement of other chromosomes in Ph formation.

Original languageEnglish
Pages (from-to)50-54
Number of pages5
JournalCancer Genetics and Cytogenetics
Issue number1
Publication statusPublished - 1993

ASJC Scopus subject areas

  • Cancer Research
  • Genetics
  • Molecular Biology


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