Leijonhufvud G, Ljungström V, Amini R-M, Saft I, Ford AM, Gustafsson B. Origins of iAMP21 in children who later developed paediatric acute lymphoblastic leukemia: an investigation of neonatal blood spots. Haematologica; https://doi.org/10.3324/haematol.2026.300813 [Early view].