PAX5 and acute lymphoblastic leukemia: Families carrying PAX5 germline alterations show phenotypically highly similar BCP-ALL with a median age of onset below 8 years of age (for p.G183S/R variants and other frameshifts/deletions) or latest up until young adulthood (for carriers of the p.R38H variant), indicating a genetically imposed limited time window of susceptibility (Supplementary Fig. 1A).