Overview of patient characteristics and genetic variations in SMNs. The subtypes of primary cancers and SMNs, intervals between primary cancers and SMNs, cancer-predisposing gene variants, and NUDT15 variants in patients with SMNs after ALL treatment are shown. NUDT15 genotype was evaluated using WES data (n = 10) and direct sequencing (n = 4). AML, acute myeloid leukemia; MDS, myelodysplastic syndrome; RT, radiation therapy.