Gestational thrombocytopenia - Reply

Although patients with essential thrombocythaemia (ET) do not have the Philadelphia chromosome t(9;22), which defines chronic myelocytic leukaemia, the chimeric BCR-ABL transcript mRNA from this translocation has been identified in patients with clinically typical essential thrombocythaemia”.These findings have been detected, by D Blickstein and colleagues2 in 48% of 25 patients negative for the Philadelphia chromosome who had essential thrombocythaemia, investigated by two-step nested RT-PCR. Some workers have not, however, been able to confirm these data by the same technique, in 18 and 20 such patients, respectively. [3] and [4] Moreover, others have shown the absence of the chimeric transcript in 41 patients with essential thrombocythaemia studied by the fluoresence in-situ hybridisation with a BCR-ABL probe.5We investigated 112 patients who had essential thrombocythaemia with long follow-up, by RT-PCR, and detected the BCR-ABL transcript in only one patient who progressed to myeloid blastic crisis 12 years after diagnosis. Actually, whether essential-thrombocythaemia patients negative for the Philadelphia chromosome express the BCR-ABL transcript has been a matter of controversy for several years. In studies, the apparent essential thrombocythaemia carrying the Philadelphia anomaly, cytogenetically or molecularly should probably be considered as a variant of chronic myelocytic leukaemia with thrombocytosis and often long survival, with obvious clinical and therapeutical implications.