blood types were discovered in 1940 by Karl
Landsteiner and Alexander Wiener. This was
40 years after
Landsteiner had discovered the ABO blood groups. Over the last half
century, we have learned far more about the processes responsible for Rh
blood group may be the most complex genetically of all blood type systems since it involves 45
different antigens on the surface of red cells that are controlled by 2
closely linked genes on chromosome 1.
Rh system was named after rhesus
monkeys, since they were initially used
in the research to make the antiserum for typing blood samples. If the
antiserum agglutinates your red cells, you are Rh+
If it doesn’t, you are
. Despite its actual genetic complexity, the inheritance of this trait
usually can be predicted by a simple
conceptual model in which there are two alleles, D and
Individuals who are homozygous dominant (DD)
or heterozygous (Dd)
are Rh+. Those who are homozygous recessive (dd)
are Rh- (i.e., they do not have the key Rh
Clinically, the Rh factor, like ABO factors, can lead to serious
medical complications. The greatest problem with the Rh group is not so much
transfusions (though they can occur) as those between a mother and her developing
fetus. Mother-fetus incompatibility occurs when the mother is
Rh- (dd) and
her fetus is Rh+ (DD or
Maternal antibodies can cross the placenta and destroy fetal red blood cells.
The risk increases with each pregnancy.
are the most likely to have this problem–13% of their newborn babies are at
Actually only about � of these babies (6% of all European births)
have complications. With preventive treatment, this number can be cut down even further.
Less than 1% of those treated have trouble.
However, Rh blood type incompatibility is still the leading cause of potentially fatal
blood related problems of the newborn. In the United States, 1 out of
1000 babies are born with this condition.
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