"New blood types are often discovered following medical disasters." Wait, what? I thought there were just 4 blood types: A, B, AB, and O. Well, with the + or -, so multiply by 2 to get 8. Oh me of such little knowledge.
First a review of what the A, B, AB, and O and the +/- represent. It was discovered a little over 100 years ago that when combining blood from different people, sometimes the red blood cells would clump together, and sometimes they wouldn't. These were grouped into 4 categories. Eventually it was figured out that there were two antigens, which were designated anti-A and anti-B. In immunology, immune system cells are referred to as having special molecules, called antibodies, generally a large, Y-shaped protein, to identify pathogenic agents. A molecule that binds to an antibody is called an antigen. This is where the A, B, AB, and O designations come from. O simply means neither anti-A nor anti-B is present.
The +/- indicates presence or absence of anti-RhD. "Rh" originally stood for "Rhesus factor", but it was subsequently discovered that the antigen being studied was not the same between humans and rhesus monkeys, so the name doesn't make sense but has stuck anyway. The "Rh" system originally had 5 antigens, one of which was designated "D". This article refers to "the Rh antigen", but the "Rh" system has actually been expanded to 49 antigens.
"Scientists discovered the Vel and Langereis blood group systems after patients suffered hemolytic reactions following transfusions."
"In 1953, a child in Venezuela died of hemolytic disease three days after birth." A blood lab identified the antigen but knew of no other person with that antigen, so they named it after the family, "Diego". It was subsequently found that the reason they had no other people with that antigen in the database was because they didn't have native Americans -- 36% of the indigenous people of South America have the antigen.
"There are only ten clinically relevant blood typing systems, and if you were to expand your blood type to include them, it might look like ABO(A+B+), Rh(D+c+e+), MNS(M+N-S+s-), P1+, Lu(a+b+), Kell(K-k+), Le(a+b-), Fy(a+b-), Jk(a+b -- ). You don't need to remember all this because physicians will test them before you get a transfusion."
"The second reason you shouldn't be concerned about a surprising reaction is that physicians no longer rely entirely on blood types to determine if blood is compatible. Instead, they use a technique called crossmatching, which involves mixing donors' serum with recipients' blood cells in a test tube. If the two are incompatible, the blood will clump."
New blood types are often discovered following medical disasters
