If this suspicion proved correct, it would make his blood type Rh null-one of the rarest in the world, and a phenomenal discovery for the hospital hematologists. But Thomas seemed to be lacking all the Rh antigens. The most important of these Rh antigens, the D antigen, is quite often missing in Caucasians, of whom around 15 percent are Rh D-negative (more commonly, though inaccurately, known as Rh-negative blood). The Rh system (formerly known as “Rhesus”) is the largest, containing 61 antigens. The majority of the 342 blood-group antigens belong to one of these systems. There are 35 blood-group systems, organized according to the genes that carry the information to produce the antigens within each system.
It will almost certainly involve a convoluted international network of people working invisibly behind the bustle of “ordinary” blood donation to track down a donor in one country and fly a bag of their blood to another.įorty years ago, when 10-year-old Thomas went into the University Hospital of Geneva with a routine childhood infection, his blood test revealed something very curious: He appeared to be missing an entire blood-group system. But when it is, finding a donor and getting the blood to a patient in crisis can become a desperate race against the clock. These transfusion reactions can be lethal.īecause so few people have it, by definition, rare blood is hardly ever needed. If you receive blood from a “positive” donor, then your own antibodies may react with the incompatible donor blood cells, triggering a further response from the immune system. If a particular high-prevalence antigen is missing from your red blood cells, then you are “negative” for that blood group. If you lack one that 99.99 percent of people are positive for, then you have very rare blood. If you lack an antigen that 99 percent of people in the world are positive for, then your blood is considered rare. Some 160 of the 342 blood-group antigens are “high-prevalence,” which means that they are found on the red blood cells of most people. It is the presence or absence of particular antigens that determines someone’s blood type. On the surface of every one of our red blood cells, we have up to 342 antigens-molecules capable of triggering the production of specialized proteins called antibodies. It would be straightforward if we all had the same blood. Hence the hundreds of millions of people flowing through blood-donation centers across the world, and the thousands of vehicles transporting bags of blood to processing centers and hospitals. If we lose a lot of blood in surgery or an accident, we need more of it-fast. Red blood cells carry oxygen to all the cells and tissues in our body. In 50 years, researchers have turned up only 40 or so other people on the planet with the same precious, lifesaving blood in their veins. Very few people in the world knew his blood type did-could-exist. Surely it was impossible for this man seated beside her to be alive, let alone apparently healthy? But when she read the details closely, her eyes widened. The nurse in Annemasse, France, could tell from the label on the blood bag destined for Paris that this blood was pretty unusual. It was quicker that way: If the man donated in Switzerland, his blood would be delayed while paperwork was filled out and authorizations sought.
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