Kidd antigen system
Encyclopedia
The Kidd antigen system is present on the membranes of red blood cells and the kidney
and helps determine a person's blood type
. The Jk antigen
is found on a protein
responsible for urea
transport in the red blood cells and the kidney. The gene
encoding this protein is found on chromosome 18. Three Jk allele
s are Jk(a), Jk(b)and Jk3. Jk (a) was discovered by Allen et al in the year 1951. Whereas Jk (b) was discovered by Plant et al in 1953. Individuals who lack the Jk antigen (Jk null) are unable to maximally concentrate their urine.
The Jk antigen is important in transfusion medicine
. People with two Jk(a) antigens, for instance, may form antibodies
against donated blood containing two Jk(b) antigens (and thus no Jk(a) antigens). This can lead to hemolytic anemia
, in which the body destroys the transfused blood, leading to low red blood cell counts. Another disease associated with the Jk antigen is hemolytic disease of the newborn
(HDN), in which a pregnant woman's body creates antibodies against the blood of her fetus, leading to destruction of the fetal blood cells. HDN associated with Jk antibodies is typically mild, though fatal cases have been reported.
Kidney
The kidneys, organs with several functions, serve essential regulatory roles in most animals, including vertebrates and some invertebrates. They are essential in the urinary system and also serve homeostatic functions such as the regulation of electrolytes, maintenance of acid–base balance, and...
and helps determine a person's blood type
Blood type
A blood type is a classification of blood based on the presence or absence of inherited antigenic substances on the surface of red blood cells . These antigens may be proteins, carbohydrates, glycoproteins, or glycolipids, depending on the blood group system...
. The Jk antigen
Antigen
An antigen is a foreign molecule that, when introduced into the body, triggers the production of an antibody by the immune system. The immune system will then kill or neutralize the antigen that is recognized as a foreign and potentially harmful invader. These invaders can be molecules such as...
is found on a protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
responsible for urea
Urea
Urea or carbamide is an organic compound with the chemical formula CO2. The molecule has two —NH2 groups joined by a carbonyl functional group....
transport in the red blood cells and the kidney. The gene
Gene
A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...
encoding this protein is found on chromosome 18. Three Jk allele
Allele
An allele is one of two or more forms of a gene or a genetic locus . "Allel" is an abbreviation of allelomorph. Sometimes, different alleles can result in different observable phenotypic traits, such as different pigmentation...
s are Jk(a), Jk(b)and Jk3. Jk (a) was discovered by Allen et al in the year 1951. Whereas Jk (b) was discovered by Plant et al in 1953. Individuals who lack the Jk antigen (Jk null) are unable to maximally concentrate their urine.
The Jk antigen is important in transfusion medicine
Transfusion medicine
Transfusion medicine is the branch of medicine that is concerned with the transfusion of blood and blood components. The blood bank is the section of the clinical laboratory where medical technologists process and distribute blood products under the supervision of a medical director, often...
. People with two Jk(a) antigens, for instance, may form antibodies
Antibody
An antibody, also known as an immunoglobulin, is a large Y-shaped protein used by the immune system to identify and neutralize foreign objects such as bacteria and viruses. The antibody recognizes a unique part of the foreign target, termed an antigen...
against donated blood containing two Jk(b) antigens (and thus no Jk(a) antigens). This can lead to hemolytic anemia
Hemolytic anemia
Hemolytic anemia is a form of anemia due to hemolysis, the abnormal breakdown of red blood cells , either in the blood vessels or elsewhere in the human body . It has numerous possible causes, ranging from relatively harmless to life-threatening...
, in which the body destroys the transfused blood, leading to low red blood cell counts. Another disease associated with the Jk antigen is 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...
(HDN), in which a pregnant woman's body creates antibodies against the blood of her fetus, leading to destruction of the fetal blood cells. HDN associated with Jk antibodies is typically mild, though fatal cases have been reported.
External links
- Kidd 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 at 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