Key points – measurement of disease burden

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  • The burden of disease (i.e. the level of BCR–ABL1 transcript) can be assessed by several methods, including full (complete) blood count, Giemsa banding karyotyping to identify presence of the Philadelphia chromosome, fluorescence in situ hybridisation, polymerase chain reaction (PCR) and next-generation sequencing.
  • The most commonly used method is quantitative reverse transcriptase PCR, which detects the ratio of abnormal BCR–ABL1 transcripts to normal ABL1 transcripts. 
  • An International Scale has been developed for standardisation of results, so that disease burden can be compared at different times even if there is variation in laboratory equipment or the quality or type of sample.