Blood groups- Important correlation about main blood groups

There are a number of characters which are more often found in one race than in another. Among these are the much debated blood groups. The discovery of these was made accidentally. While transfusion of blood from one person to another was in some cases beneficial, in other cases it brought about the sudden death of the person receiving the transfusion. Analysis indicated that there were four different main blood groups, for convenience labeled A, B, AB and O. If blood cells of group A were added to the serum of group B, instead of being evenly distributed all the cells formed clots. This happened also when the process was reversed. The same clotting occurred when serum from groups A or B were added to the cells of group AB. Yet if serum of groups A or B were added to the cells of group O, this clotting did not occur. To be successful, therefore, a transfusion can only be given when a test has been made of the donor as well as of the receiver. A list is kept by hospitals of people who belong to the blood group O, since transfusion can be made from them to any other group. To sum up, blood from group A can be given only to group A, B only to B, and O while it can be given to AB, can also be given to the other groups. Although al the blood groups are present in the five main races, group B is found more often than the other groups among Mongolians. In fact, the farther east one goes the more people there are in blood group B. Group O is found to be the only group in some tribes of South Americans. In England the two most common groups are A, B is somewhere rarer, and AB the rarest of all. These blood groups are inherited in such a way that A and B are dominant over O. Where paternity is in question, one man may often be excluded by means of a blood test. If the men involved belong to the same blood group, this method is valueless for purposes of elimination.