AFF1 and acute lymphoblastic leukemia: This contrasts sharply with most ALL studies in Mexico and globally, which rely on RT‐PCR for only the four most common gene fusions (BCR::ABL1, TCF3::PBX1, KMT2A::AFF1, and ETV6::RUNX1), yielding informative results in just 19%–45% of patients [10, 11, 12, 13, 14, 15].