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Genetics, ABO blood groups and statistics

620 views · Published 13 November 2014 · 16:54 · Indexed 10 November 2026

Channel: Nikolay's Genetics Lessons · 2014 · Education

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The most well-known and medically important blood types are in the ABO  click this icon to hear the preceding term pronounced group.  They were discovered in 1900 and 1901 at the University of Vienna by Karl Landsteiner in the process of trying to learn why blood transfusions sometimes cause death and at other times save a patient.  In 1930, he belatedly received the Nobel Prize for his discovery of blood types.

All humans and many other primates can be typed for the ABO blood group.  There are four principal types: A, B, AB, and O.  There are two antigens and two antibodies that are mostly responsible for the ABO types.  The specific combination of these four components determines an individual's type in most cases.  The table below shows the possible permutations of antigens and antibodies with the corresponding ABO type ("yes" indicates the presence of a component and "no" indicates its absence in the blood of an individual).
ABO Blood type antigens are not only found on the surface of red cells.  They are also normally secreted by some people in their body fluids, including saliva, tears, and urine.  Whether someone is able to secrete them is genetically controlled.  Police agencies now routinely use this so-called secretor system data to identify potential victims and criminals when blood samples are not available.

Despite the fact that the blood types of children are solely determined by inheritance from their parents, paternity in the U.S. and many other nations can no longer be legally established based on conventional blood typing.  To do that, it is necessary to compare HLA types and/or DNA sequences.  The use of DNA is more accurate in determining paternity, but it is also more expensive than HLA typing.

Antibodies to alien antigens in the ABO group are usually present in our plasma prior to the first contact with blood of a different ABO type.  This may be partly explained by the fact that these antigens are also produced by certain bacteria and possibly some plants.  When we come in contact with them, our bodies may develop long-term active immunity to their antigens and subsequently to the same antigens on the surface of red blood cells.  This usually occurs in babies within the first six months following their birth.

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