Acute Lymphoblastic Leukemia (ALL) is the most common malignancy diagnosed in children, accounting for approximately 25% of all childhood cancers. ALL arises from the malignant transformation of precursors from the lymphoid lineage of B cells and/or is triggered by a series of genetic aberrations, such as chromosomal translocations. These translocations initiate the leukemic process, and within B-ALL, the most clinically relevant gene fusions are BCR::ABL, TCF3::PBX1, KMT2A::AFF1, and ETV6::RUNX1.

This study aimed to evaluate the gene fusion status in B-ALL pediatric patients from the Brazilian Amazon and its association with laboratory biochemical parameters.

The research was approved by the Research Ethics Committee under protocol number 4.040.805 and included 214 patients diagnosed with ALL at the Octávio Lobo Pediatric Oncology Hospital between 2023 and 2025. Biochemical data (glucose, creatinine, urea, AST, ALT, bilirubin, and LDH) and epidemiological data (sex and age) were collected from the hospital database. For gene fusion analysis, cDNA was obtained to detect molecular biomarkers by Nested PCR using specific primers. Agarose gel electrophoresis was performed for visualization of PCR products, followed by Sanger sequencing to confirm PCR results. Descriptive statistics were used for qualitative variables, determining absolute and relative frequencies, while for quantitative variables, medians and standard deviations were calculated. The Kruskal–Wallis test was applied to assess the association between the presence of one of the gene fusions (BCR::ABL, TCF3::PBX1, KMT2A::AFF1, and ETV6::RUNX1) and biochemical parameters, adopting a significance level of p ≤ 0.05. Statistical analyses were performed using RStudio 12.1.

Of the patients, 60% were male and 40% female, with a median age of 6 years. Regarding molecular biomarkers, 35% tested positive for ETV6::RUNX1, 16% for TCF3::PBX1, 5% for BCR::ABL, 1% for KMT2A::AFF1, and 43% showed none of the studied fusions. Biochemical medians were: glucose 90 U/mL, creatinine 0.4 U/mL, urea 25.7 U/mL, AST 41.5 U/mL, ALT 26 U/mL, bilirubin 0.29 U/mL, and LDH 599 U/mL. The Kruskal–Wallis test revealed a statistically significant difference between molecular biomarkers and glucose levels (p = 0.03); no significant differences were found for other biochemical variables.

International literature reports ETV6::RUNX1 as the most frequent fusion in B-ALL, present in about 25% of cases, corroborating our findings. However, TCF3::PBX1 occurred in 16% of cases, diverging from studies in other countries that report a frequency of 3–5%. This higher prevalence in our study may be related to the high genetic admixture of the Amazonian population, potentially influencing the emergence of this fusion, and to environmental exposure to heavy metals, a common activity in the region, which may be associated with its occurrence. LDH levels were approximately seven times higher than reference values, consistent with previous studies. Elevated LDH levels are correlated with high tumor burden but are not specific for ALL, requiring interpretation alongside other laboratory findings. The ETV6::RUNX1 molecular biomarker may silence key genes and regulatory regions; thus, it is important to investigate its impact on the biochemical variables assessed in this study and its potential clinical implications throughout the three treatment phases: induction, consolidation, and maintenance.