Chimerism and mosaicism shape our physical constitution and impact medical conditions.

ABO blood group discrepancies in healthy individuals were caused by body‐wide chimerism and mosaicism. They can be evaluated with new diagnostic options for disease‐related cell clones that are typically associated with mosaicism. The observations raise the attention for sporadic mixed‐field observations of any blood group antigen. Commentary on: Dauber et al. Body‐wide chimerism and mosaicism are predominant causes of naturally occurring ABO discrepancies. Br J Haematol 2024; 205:1188‐1196 [ABSTRACT FROM AUTHOR]