Hepatotoxicity (grade 3–4 hyperbilirubinemia) requires close monitoring throughout all therapy phases due to its high frequency. Monitoring may include serum aspartate aminotransferase, alanine aminotransferase, total bilirubin, and direct bilirubin at baseline and weekly for at least 4 weeks after each peg‐asparaginase dose. Liver imaging with ultrasonography before peg‐asparaginase is advisable if the baseline LFT is abnormal or the BMI is above 30. This evidence concerns the gene GPT and Hyperbilirubinemia.