RUNX1 and leukemia: The ETV6::RUNX1 fusion gene is acquired in utero in 1–5% of newborns1, 2 and requires further oncogenic mutations for progression to overt leukemia, predominantly including copy number alterations of genes involved in B cell development or cell cycle, e.g., ETV6, PAX5, CDKN2A, and CDKN2B.3, 4, 5, 6