MNS antigen system
Encyclopedia
The MNS antigen system is a human blood group system
based upon two genes (glycophorin A
and glycophorin B
) on chromosome 4. There are currently 46 antigens in the system, but the five most important are called M, N, S, s, and U.
The system can be thought of as two separate groups: the M and N antigens are at one location on the ECM
and S, s, and U are on a closely related location. The two groups are very closely located together on chromosome
4 and are inherited as a haplotype
.
and Philip Levine
in 1927. Anti-M and anti-N antibodies are usually IgM
and are rarely associated with transfusion reactions.
Anti-N is sometimes seen in dialysis
patients due to cross-reactions with the residual formaldehyde
from sterilizing the equipment. This is usually irrelevant for transfusion since this variant of the antibody does not react at body temperature.
s and hemolytic disease of the newborn
.
The U antigen is a high incidence antigen, occurring in more than 99.9% of the population. The U was originally short for "Universal", though this is not the case. U negative RBCs can be found in people of Africa
n descent. This mutation in red cell surface structure also makes the RBCs S- and s-. Anti-U has been associated with both hemolytic transfusion reactions and hemolytic disease of the newborn.
Human blood group systems
The International Society of Blood Transfusion currently recognises 30 major blood group systems . Thus, in addition to the ABO antigens and Rhesus antigens, many other antigens are expressed on the red blood cell surface membrane...
based upon two genes (glycophorin A
GYPA
Glycophorin A , also known as GYPA, is a protein which in humans is encoded by the GYPA gene. GYPA has also recently been designated CD235a .- Function :...
and glycophorin B
GYPB
Glycophorin B also known as sialoglycoprotein delta and SS-active sialoglycoprotein is a protein which in humans is encoded by the GYPB gene...
) on chromosome 4. There are currently 46 antigens in the system, but the five most important are called M, N, S, s, and U.
The system can be thought of as two separate groups: the M and N antigens are at one location on the ECM
Extracellular matrix
In biology, the extracellular matrix is the extracellular part of animal tissue that usually provides structural support to the animal cells in addition to performing various other important functions. The extracellular matrix is the defining feature of connective tissue in animals.Extracellular...
and S, s, and U are on a closely related location. The two groups are very closely located together on chromosome
Chromosome
A chromosome is an organized structure of DNA and protein found in cells. It is a single piece of coiled DNA containing many genes, regulatory elements and other nucleotide sequences. Chromosomes also contain DNA-bound proteins, which serve to package the DNA and control its functions.Chromosomes...
4 and are inherited as a haplotype
Haplotype
A haplotype in genetics is a combination of alleles at adjacent locations on the chromosome that are transmitted together...
.
The MN group
M+ and N+ RBCs are common (75% of population) and M+N+ cells are the most common genotype (50% of population). These antigens were an early discovery and are some of the oldest blood antigens known after the ABO system. They were first described by Karl LandsteinerKarl Landsteiner
Karl Landsteiner , was an Austrian-born American biologist and physician of Jewish origin. He is noted for having first distinguished the main blood groups in 1900, having developed the modern system of classification of blood groups from his identification of the presence of agglutinins in the...
and Philip Levine
Philip Levine (physician)
Philip Levine was an imuno-hematologist whose clinical research advanced knowledge on the Rhesus factor, Hemolytic disease of the newborn and blood transfusion.-Life and career :...
in 1927. Anti-M and anti-N antibodies are usually IgM
IGM
IGM as an acronym or abbreviation can refer to:* Immunoglobulin M , the primary antibody against A and B antigens on red blood cells* International Grandmaster, a chess ranking* intergalactic medium* Intragroup medium - see: Intracluster medium...
and are rarely associated with transfusion reactions.
Anti-N is sometimes seen in dialysis
Dialysis
In medicine, dialysis is a process for removing waste and excess water from the blood, and is primarily used to provide an artificial replacement for lost kidney function in people with renal failure...
patients due to cross-reactions with the residual formaldehyde
Formaldehyde
Formaldehyde is an organic compound with the formula CH2O. It is the simplest aldehyde, hence its systematic name methanal.Formaldehyde is a colorless gas with a characteristic pungent odor. It is an important precursor to many other chemical compounds, especially for polymers...
from sterilizing the equipment. This is usually irrelevant for transfusion since this variant of the antibody does not react at body temperature.
The U and Ss groups
The S antigen is relatively common (~55% of the population) and the s antigen is very common (~89% of the population). Anti-S and anti-s can cause hemolytic transfusion reactionHemolytic transfusion reaction
An acute hemolytic transfusion reaction is a type of transfusion reaction that is associated with hemolysis.It occurs very soon after the transfusion. It can occur quickly upon transfusing a few milliliters, or up to 1-2 hours post-transfusion...
s and hemolytic disease of the newborn
Hemolytic disease of the newborn
Hemolytic disease of the newborn, also known as hemolytic disease of the fetus and newborn, HDN, HDFN, or erythroblastosis fetalis, is an alloimmune condition that develops in a fetus, when the IgG molecules produced by the mother pass through the placenta...
.
The U antigen is a high incidence antigen, occurring in more than 99.9% of the population. The U was originally short for "Universal", though this is not the case. U negative RBCs can be found in people of Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
n descent. This mutation in red cell surface structure also makes the RBCs S- and s-. Anti-U has been associated with both hemolytic transfusion reactions and hemolytic disease of the newborn.
Other MNS antigens
The other 41 identified antigens in the MNS group are low incidence, such as He (0.8% of the population) or high incidence, such as ENa (>99.9% of the population).External links
- MNS system at BGMUTBGMUTThe BGMUT Database documents allelic variations in the genes encoding for human blood group systems. It was set up in 1999 through an initiative of the Human Genome Variation Society . Since 2006, it has been a part of the dbRBC resource of NCBI at the NIH...
Blood Group Antigen Gene Mutation Database, NCBINational Center for Biotechnology InformationThe National Center for Biotechnology Information is part of the United States National Library of Medicine , a branch of the National Institutes of Health. The NCBI is located in Bethesda, Maryland and was founded in 1988 through legislation sponsored by Senator Claude Pepper...
, NIH