Cytogenomic Abnormalities in Children With Acute Lymphoblastic Leukemia From Western Mexico: A Single-Center Fluorescence In Situ Hybridization-Based Study.

In Mexico, the 5-year overall survival (OS) rate for pediatric acute lymphoblastic leukemia (ALL) ranges from 45% to 85%, markedly lower than the ∼90% reported in high-income countries, where cytogenomic testing is essential for accurate risk stratification and therapeutic decision-making. The few available data for Mexican cohorts derive from studies conducted in Mexico City using conventional karyotyping, DNA index analysis, and RT-PCR targeting only four gene fusions. Broader cytogenomic characterization is needed to identify additional prognostic alterations. We analyzed 170 pediatric ALL cases (150 B-Cell lineage, 10 T-Cell lineage, and 10 mixed phenotype) using fluorescence in situ hybridization (FISH) with a panel of 11 probe sets targeting recurrent cytogenomic abnormalities. All patients were treated according to the Total XV protocol. Among 150 B-Cell ALL cases, recurrent cytogenomic abnormalities included ETV6::RUNX1 (n = 19), TCF3::PBX1 (n = 7), BCR::ABL1 (n = 5), KMT2A::V (n = 10), IGH::V (n = 7), V::CRLF2 (n = 11), iAMP21 (n = 8), and deletions involving CDKN2A/B (n = 38), TP53 (n = 7), RB1 (8), ATM (n = 1), and ETV6 (n = 15). Hypodiploidy (n = 2), high-hyperdiploidy (n = 38), low-hyperdiploidy (n = 16), and 1q gain (n = 14) were also identified. Our findings reveal a cytogenomic landscape characterized by a predominance of high-risk abnormalities such as iAMP21 and KMT2A::V, together with a lower frequency of low-risk alterations like ETV6::RUNX1. The frequent coexistence of secondary abnormalities further supports the relevance of comprehensive cytogenomic profiling for accurate risk assessment. The high diagnostic coverage and rapid turnaround of the FISH-based approach underscore its value as a reliable and efficient diagnostic tool in newly diagnosed ALL. The authors have confirmed clinical trial registration is not needed for this submission.