Busulfan-induced loss of Ph chromosome in chronic myeloid leukemia

We report a 44-yr-old female with Philadelphia chromosome positive chronic myeloid leukemia who was initially treated with busulfan, and clinical remi ssion has been achieved. After 4 yr, low-dose busulfan therapy was started again and induced bone marrow aplasia. The patient spontaneously has recove red from aplasia, and complete cytogenetic remission with loss of Ph+ chrom osome in bone marrow has been achieved. However, reverse-transcription - po lymerase chain reaction analysis showed presence of the bcr-abl transcript in bone marrow.