The MLL product consists of an 87kb probe, labelled in red, covering a region telomeric to the MLL (KMT2A) gene including the marker SHGC-111513 and a green probe covering a 170kb region centromeric to the MLL gene spanning the CD3G and UBE4A genes.
The KMT2A (lysine methyltransferase 2A) gene at 11q23.3 is commonly rearranged in acute leukaemias, especially in infant leukaemia and in secondary leukaemia, following treatment with DNA topoisomerase II inhibitors1.
The KMT2A gene has a great homology with the drosophila trithorax gene and encodes for a histone methyltransferase, which functions as an epigenetic regulator of transcription. KMT2A translocations result in the production of a chimeric protein in which the amino-terminal portion of KMT2A is fused to the carboxy-terminal portion of the fusion partner gene. The functional protein plays a critical role in embryonic development and haematopoiesis1,2,3,4.
KMT2A rearrangements can be detected in approximately 80% of infants with acute lymphoblastic leukaemia (ALL) and in 5-10% of paediatric and adult ALLs3,4. They can also be found in 60% of infant acute myeloid leukaemia (AML) and in 3% of de novo and 10% of therapy related adult AML cases3,5. To date, more than 70 partners have been identified with the most common translocations being MLL::AFF1; t(4;11)(q21;q23.3), MLL::MLLT4; t(6;11)(q27;q23.3), MLL::MLLT3; t(9;11) (p22;q23.3) and MLL::MLLT1; t(11;19)(q23.3;p13.3)1.
Historically, KMT2A rearrangements in acute leukaemia were associated with a poorer outcome, but recent studies have shown that the prognosis is highly dependent on the fusion partner and it may differ between children and adults1.
The CytoCell® MLL (KMT2A) Breakapart Probe is a qualitative, non-automated, fluorescence in situ hybridisation (FISH) test used to detect chromosomal rearrangements in the 11q23.3 region on chromosome 11 in Carnoy’s solution (3:1 methanol/acetic acid) fixed haematologically-derived cell suspensions from patients with confirmed or suspected acute myeloid leukaemia (AML), myelodysplastic syndromes (MDS), or acute lymphoblastic leukaemia (ALL).
This device is designed as an adjunct to other clinical and histopathological tests in recognised diagnostic and clinical care pathways, where knowledge of MLL (KMT2A) rearrangement status would be important for clinical management.
This device is designed to detect rearrangements with breakpoints in the region bounded by the red and green clones in this probe set, which includes the MLL (KMT2A) gene. Breakpoints outside of this region, or variant rearrangements wholly contained within this region, may not be detected with this device.
This device is not intended for: use as a stand-alone diagnostic, use as a companion diagnostic, prenatal testing, population-based screening, near-patient testing, or self-testing.
This device has not been validated for sample types, disease types, or purposes outside of those stated in the intended use.
It is intended as an adjunct to other diagnostic laboratory tests and therapeutic action should not be initiated on the basis of the FISH result alone.
Reporting and interpretation of FISH results should be performed by suitably qualified staff, consistent with professional standards of practice, and should take into consideration other relevant test results, clinical and diagnostic information.
This device is intended for laboratory professional use only.
Failure to adhere to the protocol may affect the performance and lead to false positive/negative results.
We have successfully used CytoCell haematology probes over the last 5 years and were looking for the same quality and consistency for our FISH pathology screening. OGT worked closely with us to help our lab evaluate – and later validate – CytoCell pathology probes. CytoCell is now our primary FISH probe supplier. Results have been excellent and we were able to consolidate our workflow to follow a single, streamlined protocol.
Dr Mary Nordberg
Molecular Pathology Director, Delta Pathology Group, USA