PAX5 and precursor B-cell acute lymphoblastic leukemia: This study found two distinct subtypes of B-ALL characterized by PAX5 alterations: the first (n=148) which harbor diverse PAX5 alterations (including rearrangements, sequence mutations, and focal intragenic amplifications) and the second (n=44) which harbor a particular nonsilent sequence mutation, PAX5 p.Pro80Arg.