PBX1 and acute lymphoblastic leukemia: Other observed genetic markers not relevant for risk stratification within the AIEOP-BFM ALL 2017 trial were as follows: TCF3 rearrangement (n = 3; TCF3-PBX1 fusions), KMT2A rearrangement (n = 1; KMT2A-MLLT1 fusion; aberration is only relevant for stratification in cases < 1 year of age), and hyperdiploid karyotype with more than 50 chromosomes (n = 35).