Philadelphia chromosome-positive de novo myelodysplastic syndrome with the p230 BCR::ABL1 fusion gene: a case report.

De novo Ph-positive MDS with the micro BCR::ABL1 (e19a2/p230) transcript is rare. Here, we report a case of MDS with multilineage dysplasia in an 86-year-old woman. Reverse transcription polymerase chain reaction (RT-PCR) showed the following karyotype: 46, XX, t(9;22)(q34.1;q11.2), i(17)(q10) [20], and p230 BCR::ABL1. Targeted NGS at diagnosis revealed mutations in CSF3R, BCOR, SRSF2, and ASXL1. Low-dose dasatinib (20 mg/day) reduced BCR::ABL1 levels (FISH negative, RT-PCR positive), but had no effect on anemia, dysplasia, or transfusion frequency. At six months, panel results showed loss of all mutations except ASXL1, as well as clearance of Ph-positive subclones. However, an ASXL1 founder clone persisted. Post-treatment chromosome analysis was not feasible because of poor cell growth. Serial genomics suggested that Ph positivity was a late/secondary event on a pre-existing ASXL1-mutant background. In Ph-positive de novo MDS, BCR::ABL1 transcript responses alone may not reflect disease control when an adverse founder clone persists. Integrating panel-based NGS with fusion transcript monitoring may improve therapeutic decision-making and prognostic assessment.