Childhood B-ALL t(12;21)
46,XX,t(12;21)(p13;q22)
Also known as: ETV6-RUNX1, TEL-AML1, t(12;21)
46,XX,t(12;21)(p13;q22) fuses ETV6 with RUNX1 and is the most common recurrent translocation in childhood B-cell acute lymphoblastic leukemia. It usually carries a favorable prognosis and is often cryptic on banding, requiring FISH or molecular testing.
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What the notation means
46- total chromosome count (the normal human number)
XX- sex chromosomes: two X (usual female karyotype)
t(12;21)(p13;q22)- a reciprocal TRANSLOCATION: chromosomes 12 and 21 break (at 12p13 and 21q22) and swap the pieces beyond those breaks, giving two derivative chromosomes der(12) and der(21)
Clinical notes
t(12;21), Childhood B-ALL
t(12;21)(p13;q22) fuses ETV6::RUNX1 (TEL-AML1), the most common recurrent translocation in childhood B-cell ALL; generally favorable prognosis and often cryptic on banding (needs FISH).