Ewing sarcoma t(11;22)
46,XY,t(11;22)(q24;q12)
Also known as: EWSR1-FLI1, t(11;22), Ewing family tumor
46,XY,t(11;22)(q24;q12) is the defining translocation of Ewing sarcoma, fusing EWSR1 on chromosome 22 with FLI1 on chromosome 11. It accounts for most cases, and the fusion is what separates Ewing sarcoma from the other small round blue cell tumors of childhood.
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What the notation means
46- total chromosome count (the normal human number)
XY- sex chromosomes: one X, one Y (usual male karyotype)
t(11;22)(q24;q12)- a reciprocal TRANSLOCATION: chromosomes 11 and 22 break (at 11q24 and 22q12) and swap the pieces beyond those breaks, giving two derivative chromosomes der(11) and der(22). The pieces that move are the tips, which carry no centromere; each derivative keeps the centromere it started with, and that is the chromosome it is named for
Clinical notes
t(11;22), Ewing sarcoma
EWSR1::FLI1. Ewing sarcoma and the Ewing family of tumours. About eighty-five per cent of Ewing sarcoma; t(21;22) EWSR1::ERG accounts for most of the rest. A small round blue cell tumour with membranous CD99, where the fusion is what separates it from lymphoblastic lymphoma and rhabdomyosarcoma. EWSR1 break-apart FISH is positive across several unrelated sarcomas, so the partner matters.