The Augustine blood group system is a

human blood group system 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 ...

. It includes four

red blood cell Red blood cells (RBCs), also referred to as red cells, red blood corpuscles (in humans or other animals not having nucleus in red blood cells), haematids, erythroid cells or erythrocytes (from Greek ''erythros'' for "red" and ''kytos'' for "holl ...

surface

glycoprotein Glycoproteins are proteins which contain oligosaccharide chains covalently attached to amino acid side-chains. The carbohydrate is attached to the protein in a cotranslational or posttranslational modification. This process is known as g ...

antigens In immunology, an antigen (Ag) is a molecule or molecular structure or any foreign particulate matter or a pollen grain that can bind to a specific antibody or T-cell receptor. The presence of antigens in the body may trigger an immune response. ...

which are encoded by

alleles An allele (, ; ; modern formation from Greek ἄλλος ''állos'', "other") is a variation of the same sequence of nucleotides at the same place on a long DNA molecule, as described in leading textbooks on genetics and evolution. ::"The chro ...

of the gene

SLC29A1 Equilibrative nucleoside transporter 1 (ENT1) is a protein that in humans is encoded by the ''SLC29A1'' gene. Multiple alternatively spliced variants, encoding the same protein, have been found for this gene. Expressed on red blood cell surfaces, ...

Antigens

The protein which acts as the Augustine antigens is

equilibrative nucleoside transporter 1 Equilibrative nucleoside transporter 1 (ENT1) is a protein that in humans is encoded by the ''SLC29A1'' gene. Multiple alternatively spliced variants, encoding the same protein, have been found for this gene. Expressed on red blood cell surfaces, t ...

, a transmembrane

that mediates cellular uptake of

nucleoside Nucleosides are glycosylamines that can be thought of as nucleotides without a phosphate group. A nucleoside consists simply of a nucleobase (also termed a nitrogenous base) and a five-carbon sugar ( ribose or 2'-deoxyribose) whereas a nucleoti ...

s. This protein is abundant in

erythroid progenitor cells Hematopoietic stem cells (HSCs) are the stem cells that give rise to other blood cells. This process is called haematopoiesis. In vertebrates, the very first definitive HSCs arise from the ventral endothelial wall of the embryonic aorta within t ...

and in mature red blood cells. There are four known variants of the antigen: AUG1, AUG2, AUG3, and AUG4. One person may express multiple variants; AUG:1,2,4 (expressing AUG1, AUG2, and AUG4) is the common

phenotype In genetics, the phenotype () is the set of observable characteristics or traits of an organism. The term covers the organism's morphology or physical form and structure, its developmental processes, its biochemical and physiological prop ...

Clinical significance

Antibodies against Augustine system antigens can be stimulated by pregnancy or

blood transfusion Blood transfusion is the process of transferring blood products into a person's circulation intravenously. Transfusions are used for various medical conditions to replace lost components of the blood. Early transfusions used whole blood, but m ...

and have the potential to cause severe

hemolytic disease of the fetus and newborn Hemolytic disease of the newborn, also known as hemolytic disease of the fetus and newborn, HDN, HDFN, or erythroblastosis foetalis, is an alloimmune condition that develops in a fetus at or around birth, when the IgG molecules (one of the five ...

and

acute hemolytic transfusion reaction An acute hemolytic transfusion reaction (AHTR), also called immediate hemolytic transfusion reaction, is a life-threatening reaction to receiving a blood transfusion. AHTRs occur within 24 hours of the transfusion and can be triggered by a few milli ...

s. In red blood cells, the Augustine antigen protein seems to play a role in

adenosine Adenosine (symbol A) is an organic compound that occurs widely in nature in the form of diverse derivatives. The molecule consists of an adenine attached to a ribose via a β-N9-glycosidic bond. Adenosine is one of the four nucleoside buildin ...

transport in

cell differentiation Cellular differentiation is the process in which a stem cell alters from one type to a differentiated one. Usually, the cell changes to a more specialized type. Differentiation happens multiple times during the development of a multicellula ...

, when immature cells become red blood cells. Individuals with the null phenotype, lacking any form of the transporter protein, have

mineralization Mineralization may refer to: * Mineralization (biology), when an inorganic substance precipitates in an organic matrix ** Biomineralization, a form of mineralization ** Mineralization of bone, an example of mineralization ** Mineralized tissues ar ...

around the joints,

ectopic calcification Ectopic calcification is a pathologic deposition of calcium salts in tissues or bone growth in soft tissues. This can be a symptom of hyperphosphatemia. Formation of osseous tissue in soft tissues such as the lungs, eyes, arteries, or other organs ...

, and abnormal red blood cells.

History

AUG2 was first identified as At^a in 1967 as a common human antigen. The SLC29A1 gene was identified in 1997 and found to encode AUG1 and AUG2 in 2015. In response to the 2015 discovery, the

International Society of Blood Transfusion The International Society of Blood Transfusion (ISBT) is a scientific society founded in 1935, which promotes the study of blood transfusion and spreads reliable information about the ways in which blood transfusion medicine and science can bes ...

established the Augustine blood system as the 36th human blood group system. AUG3 and AUG4 were identified in 2018. The blood group system was named Augustine after the surname of the individual with the first identified anti-At^a antibody, a woman of African ancestry whose third child had a positive

direct antiglobulin test A Coombs test, also known as antiglobulin test (AGT), is either of two blood tests used in immunohematology. They are the direct and indirect Coombs tests. The direct Coombs test detects antibodies that are stuck to the surface of the red blood ce ...

at birth.

References

{{transfusion medicine Blood antigen systems Transfusion medicine Genes on human chromosome 6