AML1, 21q22.12, Red
AML1, 21q22.12, Green
The AML1 probe mix consists of a 156kb probe, labelled in red, centromeric to the AML1 (RUNX1) gene that spans the CLIC6 gene and a 169kb probe, labelled in green, covering part of the AML1 (RUNX1) gene, including markers SHGC-87606 and D21S1921.
The RUNX1 (RUNX family transcription factor 1) gene at 21q22.12 is one of the most frequent targets of chromosomal rearrangements observed in human acute leukaemia.
The most common rearrangements are the ETV6-RUNX1 and RUNX1-RUNX1T1 fusions. The ETV6-RUNX1 fusion is brought about by the t(12;21)(p13;q22) translocation, observed in around 21% of childhood B-cell acute lymphoblastic leukaemia (ALL) cases1, whilst the RUNX1- RUNX1T1 fusion is the result of the t(8;21)(q22;q22) translocation observed in 10-22% of patients with acute myeloid leukaemia (AML) FAB (French-American-British classification) type M2 and 5-10% of AML cases overall2,3. Both these rearrangements are considered good prognostic indicators in these diseases4,5.
The RUNX1 gene is also rearranged in many other rarer translocations, with partners including chromosomes 1, 2, 3, 4, 5, 6, 7, 9, 10, 14, 15, 16, 17, 18, 19, 20 and X6. This breakapart probe has been designed to allow the detection of rearrangements regardless of the partner gene.
Rearrangements of RUNX1 are not restricted to translocations. Using FISH, amplifications of chromosome 21 (iAMP21), including the RUNX1 gene, have also been found in childhood ALL7,8. These amplifications have been associated with poorer outcome9.
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