In the ISCN notation for a MLL FISH signal pattern of 1F 1R 1G, what is the correct interpretation?

The ISCN notation provides a standardized method for describing fluorescence in situ hybridization (FISH) results, particularly for chromosome abnormalities related to specific genes like MLL. In the notation presented—1F 1R 1G—the numbers signify the number of fluorescent signals detected for the probes used.

When interpreting the notation for 1F 1R 1G, the presence of one fusion signal (F), one red signal (R), and one green signal (G) suggests a specific arrangement of gene signals related to the MLL gene. The interpretation given in the correct choice details that there are two copies of the gene indicated by the notation (MLLx2), a separation (sep) indicated between the first and the second set (5?MLL) possibly implying uncertainty regarding one signal's status.

The use of "5?" indicates a questioned status—possibly representing an incomplete or ambiguous signal. The notation structure of "MLL sep 3?MLLx1" suggests that while three signals of uncertain origin are noted, there's still one definitive location where the MLL gene is located.

In summary, this interpretation encapsulates the findings succinctly, describing two definite MLL signals, uncertainty about additional signals, and the