Rh null individuals have no Rh antigens (no Rh or RhAG) on their red blood cells. As a consequence of the absence of Rh antigens, Rh null red blood cells also lack LW and Fy5 and show weak expression of S, s, and U antigens.
Red blood cells lacking Rh/RhAG proteins have structural abnormalities (such as stomatocytosis) which can result in hemolytic anemia.
Rhnull blood was first described in 1961, in an Aboriginal Australian woman. Until then, doctors had assumed that an embryo missing all Rh blood-cell antigens would not survive, let alone grow into a normal, thriving adult. By 2010, nearly five decades later, some 43 people with Rhnull blood had been reported worldwide.
Researchers seeking to unravel the mysteries of the physiological role of the intriguingly complex Rh system are keen to get hold of Rhnull blood, as it offers the perfect “knockout” system. Rare negative blood is so sought after for research that even though all samples stored in blood banks are anonymized, there have been cases where scientists have tried to track down and approach individual donors directly to ask for blood.
And because Rhnull blood can be considered “universal” blood for anyone with rare blood types within the Rh system, its life-saving capability is enormous. As such, it’s also highly prized by doctors—although it will be given to patients only in extreme circumstances, and after very careful consideration, because it may be nigh on impossible to replace. “It’s the golden blood,” says Dr. Thierry Peyrard, the current Director of the National Immunohematology Reference Laboratory in Paris.
Blood groups are inherited, and Rhnull is known to run in families.