PTPN21 and acute lymphoblastic leukemia: Xiao H et al. [14] conducted a comprehensive whole-exome sequencing analysis in three adult patients with Ph- B-cell ALL (Ph- B-ALL) using samples from diagnosis to relapse after allogeneic hematopoietic stem cell transplantation (allo-HSCT) and discovered PTPN21 mutations in the samples obtained during relapse.