Interpretation

The assay is reported in the form of a normalized ratio of RUNX1-RUNX1T1 fusion transcript to the control gene ABL1 expressed as a percentage, which is an estimate of the level of RUNX1-RUNX1T1 fusion RNA present in the specimen, expressed in relation to the level of RNA from an internal control gene (ABL1). The normalized ratio has no units but is directly related to the level of RUNX1-RUNX1T1 detected (ie, larger numbers indicate higher relative levels of RUNX1-RUNX1T1 and smaller numbers indicate lower levels). A relative expression value minimizes variability in the RNA levels and cell numbers measured in separate specimens tested at different times. The precision of the quantitative assay is excellent, but interassay variability can occur such that result changes should not be considered significant if 2 single measurements differ by less than 0.5 log. More critical results, such as a change in the status of positivity or 1 log or greater increase between 2 positive samples should be repeated on a separate specimen with appropriate time interval to verify the result.