There are some interesting facts of human blood. Recently, I have read some articles of different blood types and the compatibility. Many of us might know a little of these facts. The transfusion of animal blood into human was first attempted sometime around 1600. These experiments were proven disastrous. In 1900, the 4 major blood types (AB, A, B and O) were identified by Karl Landsteiner. This is why today we have the blood bank all over the world, providing some blood donation and services to people who really need them.


Caption: blood cells

Anyway, the 4 main blood types were divided into 8 different types: AB, AB-, A+, A-, B+, B-, O+ and O-. The picture in the below explained the four types of blood. Clearly seen in the below, there are distinct molecules called agglutinogens attached to the surface of the red blood cells. A broader level of specificity added to the blood type chart. This is done by examining the presence or absence of the Rh protein in our blood. Each blood type were subcategorised either in positive (+) or negative (-). A positive blood type shows that the person's blood contained the Rh protein. On the other hand, negative blood type by mean no Rh protein. For example, a person whose blood type is B+ has both B and Rh proteins on the surface of their red blood cells. This is why there are some restrictions for recipients from donors, depending on their blood type.


Caption: molecules and red blood cells


Caption: blood types compatibility chart

I think this is quite general, and therefore, I will only explain briefly. The chart above shows that recipients may only receive blood from compatible blood donors, such as: recipients with 0- blood type may only accept blood from O- blood type donors. AB receipients on the other hand may accept blood from any blood donors. According to research, there are only approximate 7% people on earth having O- blood type. This makes it much more difficult for people to look for blood donors for this blood type.


Caption: ABO blood plasma chart

Okay, this is interesting. Blood type is genetic. The A and B blood type are called codomimant alleles. In other words, the A and B antigen molecules on the red blood cell surface are produced by 2 different enzymes. O blood type is recessive, it is not apparent if the person inherits an A or B allele along with it. Therefore, this has generate some possibilities of blood combinations in particular blood type. Since everyone on earth inherit their blood type from their parents, there are some possible outcome of blood type from these combinations. For example, Mr. A whose dad has O blood type whilst his mom has a A blood type. The usual outcome is A blood type for Mr. A. However, I will not deny some other possibilities of Mr. A having O blood type, since there are random issues, specifying the combination of A (mom) + O (dad) blood type may result in O. However, this is certain. If one of your parents has O blood type, you (and / or your siblings) can NEVER have AB blood type as outcome. If they do, then something dealing with their DNA is definitely wrong.


Caption: blood type and inheritance

The Rh value in the red blood cells work similarly to blood type groups. If you are Rh (+), you may have genes for both positive and negative. If you are Rh (-), you have two genes for Rh negative. In the chart above, the child's Rh value is written in the white area.