The t(9;22) translocation in Philadelphia-positive essential thrombocythaemia does not involve the T lymphocyte lineage

Acta Haematol. 1990;83(4):203-5. doi: 10.1159/000205214.


A 42-year-old woman presented with clinical and haematological features of essential thrombocythaemia (ET). Cytogenetic investigation revealed a standard t(9;22) Philadelphia translocation in all evaluable metaphases which persisted throughout treatment. Gene probe analysis of the chromosome 22 breakpoint cluster region (bcr) locus revealed a breakpoint mapping between exons 1 and 3 of the bcr gene, consistent with a standard bcr-abl translocation as found in chronic myeloid leukaemia (CML). Moreover, in separate cell populations, the bcr breakpoint was demonstrable in DNA from granulocytes but not in T cells from either peripheral blood or bone marrow. Since ET is known to be a clonal disorder with a multipotential stem cell origin, these findings suggest that, as in CML, the bcr-abl hybrid gene arises through translocation in a multilineage stem cell which does not involve the T lymphocyte lineage.

Publication types

  • Case Reports
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Antigens, CD / analysis
  • Antigens, Differentiation, T-Lymphocyte / analysis
  • CD3 Complex
  • Chromosomes, Human, Pair 22*
  • Chromosomes, Human, Pair 9*
  • DNA / blood
  • DNA / genetics
  • Female
  • Humans
  • Nucleic Acid Hybridization
  • Philadelphia Chromosome*
  • Receptors, Antigen, T-Cell / analysis
  • T-Lymphocytes / immunology*
  • T-Lymphocytes / pathology
  • Thrombocythemia, Essential / blood
  • Thrombocythemia, Essential / genetics*
  • Thrombocythemia, Essential / immunology
  • Translocation, Genetic*


  • Antigens, CD
  • Antigens, Differentiation, T-Lymphocyte
  • CD3 Complex
  • Receptors, Antigen, T-Cell
  • DNA