Overview
- Rh-null, known as “golden blood,” lacks all Rh antigens and is the rarest known blood type, with estimates of roughly one in six million and fewer than about 50 identified cases.
- It can serve as a highly flexible donor source for patients with rare or multiple Rh antibodies, offering compatibility that can exceed O negative in specific transfusion scenarios.
- Carriers face severe transfusion risk from non–Rh-null blood and commonly manage hemolytic anemia, so clinical guidance stresses self-donation and long-term frozen storage.
- International teams are exploring lab production using CRISPR-Cas9, induced pluripotent stem cells, and cell lines from rare donors, including projects linked to Bristol, Versiti, Laval, Barcelona, and Scarlet Therapeutics.
- The first-in-human RESTORE trial is assessing the safety of lab-grown red blood cells, but large-scale, fully compatible production remains constrained by maturation, membrane integrity, cost, and regulatory hurdles.