Novel BCR-ABL transcript containing an intronic sequence insert in a patient with Philadelphia-positive acute lymphoblastic leukaemia

In a patient with Philadelphia chromosome-positive acute lymphoblastic leuk aemia (ALL), a novel variant of the chimaeric BCR-ABL mRNA transcript was d etected by reverse transcription polymerase chain reaction (RT-PCR). Sequen cing revealed the novel transcript to be a chimaeric mRNA produced by fusio n of the BCR exon 14 (b3) to the ABL exon a2 with a 49-base pair (bp) inser tion of an ABL intron 1b sequence between them. The insertion of the 49 bp introduced a stop codon. These data show that this variant of the chimaeric mRNA would not be translated into the p210 BCR-ABL protein. This could be one of the explanations as to why clinically the patient has responded well to therapy and continues to follow a mild clinical course.