XK (also known as Kell blood group precursor) is a

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respon ...

found on human

red blood cells 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 ...

and other tissues which is responsible for the Kx

antigen 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 helps determine a person's

blood type A blood type (also known as 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, carbohydrat ...

Clinical significance

The Kx antigen plays a role in matching blood for

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 ...

s. Mutation of XK protein may lead to

McLeod syndrome McLeod syndrome (pronounced ) is an X-linked recessive genetic disorder that may affect the blood, brain, peripheral nerves, muscle, and heart. It is caused by a variety of recessively inherited mutations in the XK gene on the X chromosome. The ...

, a multi-system disorder characterized by

hemolytic anemia Hemolytic anemia or haemolytic anaemia is a form of anemia due to hemolysis, the abnormal breakdown of red blood cells (RBCs), either in the blood vessels (intravascular hemolysis) or elsewhere in the human body (extravascular). This most commonly ...

myopathy In medicine, myopathy is a disease of the muscle in which the muscle fibers do not function properly. This results in muscular weakness. ''Myopathy'' means muscle disease (Greek : myo- ''muscle'' + patheia '' -pathy'' : ''suffering''). This mea ...

acanthocytosis Acanthocyte (from the Greek word ἄκανθα ''acantha'', meaning 'thorn'), in biology and medicine, refers to an abnormal form of red blood cell that has a spiked cell membrane, due to thorny projections. A similar term is spur cells. Often ...

, and

chorea Chorea (or choreia, occasionally) is an abnormal involuntary movement disorder, one of a group of neurological disorders called dyskinesias. The term ''chorea'' is derived from the grc, χορεία ("dance"; see choreia), as the quick movement ...

. XK is located on the

X chromosome The X chromosome is one of the two sex-determining chromosomes ( allosomes) in many organisms, including mammals (the other is the Y chromosome), and is found in both males and females. It is a part of the XY sex-determination system and XO se ...

(cytogenetic band Xp21.1) and absence of the XK protein is an X-linked disease.

Function

XK is a

membrane transport In cellular biology, membrane transport refers to the collection of mechanisms that regulate the passage of solutes such as ions and small molecules through biological membranes, which are lipid bilayers that contain proteins embedded in them. ...

protein of unknown action.

References

External links

GeneReviews/NCBI/NIH/UW entry on McLeod Neuroacanthocytosis Syndrome

XK
at

BGMUT The BGMUT (Blood Group antigen gene MUTation) 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 ( HGVS). Since 2006, it has b ...

Blood Group Antigen Gene Mutation Database at

NCBI The National Center for Biotechnology Information (NCBI) is part of the United States National Library of Medicine (NLM), a branch of the National Institutes of Health (NIH). It is approved and funded by the government of the United States. The ...

NIH The National Institutes of Health, commonly referred to as NIH (with each letter pronounced individually), is the primary agency of the United States government responsible for biomedical and public health research. It was founded in the late 1 ...

* {{transfusion medicine Blood antigen systems Transfusion medicine