TCF3 and Down syndrome: The most frequent genetic feature was ETV6::RUNX1 (18.83%), followed by hyperdiploidy (10.31%) and TCF3::PBX1 (5.38%); less common mutations were BCR::ABL1 (4.47%), KMT2A rearrangements (1.34%) and SIL::TAL1 (0.89%); the incidence of Down syndrome was 1.34% and there were no patients with hypodiploidy.