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Blood type (also called a blood group) is a classification of blood, based on the presence and absence of antibodies and inherited antigenic substances on the surface of red blood cells (RBCs). These antigens may be proteins, carbohydrates, glycoproteins, or glycolipids, depending on the blood group system.
A complete blood type would describe each of the 45 blood groups, and an individual's blood type is one of many possible combinations of blood-group antigens. [3] Almost always, an individual has the same blood group for life, but very rarely an individual's blood type changes through addition or suppression of an antigen in infection, malignancy, or autoimmune disease.
The "O" blood type (usually resulting from the absence of both A and B alleles) is very common around the world, with a rate of 63% in all human populations. [135] Type "O" is the primary blood type among the Indigenous populations of the Americas, particularly within Central and South American populations, with a frequency of nearly 100%. [135]
The A blood type contains about 20 subgroups, of which A1 and A2 are the most common (over 99%). A1 makes up about 80% of all A-type blood, with A2 making up almost all of the rest. [38] These two subgroups are not always interchangeable as far as transfusion is concerned, as some A2 individuals produce antibodies against the A1 antigen.
The Lutheran antigen systems is a classification of human blood based on the presence of substances called Lutheran antigens on the surfaces of red blood cells. There are 19 known Lutheran antigens. [1] The name Lutheran stems from a blood donor's misspelled last name, reportedly named Lutteran or Lutheran.
The genetic history of North Africa encompasses the genetic history of the people of North Africa.The most important source of gene flow to North Africa from the Neolithic Era onwards was from Western Asia, while the Sahara desert to the south and the Mediterranean Sea to the north were also important barriers to gene flow from sub-Saharan Africa and parts of Europe in prehistory.
There are two main types of Lewis antigens, Lewis a (Le-a) and Lewis b (Le-b). There are three common phenotypes: Le(a+b-), Le(a-b+), and Le(a-b-). [2] The enzyme fucosyltransferase 3 (FUT3), encoded by Le gene, adds a fucose to the precursor oligosaccharide substrate, converting it to the Le-a antigen. People who have the Le allele and who are ...
The term human blood group systems is defined by the International Society of Blood Transfusion (ISBT) as systems in the human species where cell-surface antigens—in particular, those on blood cells—are "controlled at a single gene locus or by two or more very closely linked homologous genes with little or no observable recombination between them", [1] and include the common ABO and Rh ...