HBD

HBD
Available structures
PDB	Human UniProt search: PDBe RCSB
List of PDB id codes
	1SHR, 1SI4
Identifiers
Aliases	HBD , hemoglobin subunit delta
External IDs	OMIM: 142000 HomoloGene: 128037 GeneCards: HBD
Gene location (Human)
Chr.	Chromosome 11 (human)
End	5,243,657 bp
RNA expression pattern
	Top expressed in
	cancellous bone; ; bone marrow; ; bone marrow cells; ; monocyte; ; blood; ; vena cava; ; endothelial cell; ; periodontal fiber; ; spleen; ; superficial temporal artery;
	n/a
	More reference expression data
	n/a
Gene ontology
Molecular function	iron ion binding ; oxygen binding ; protein binding ; heme binding ; metal ion binding ; oxygen carrier activity ; peroxidase activity ; haptoglobin binding ; hemoglobin alpha binding ; organic acid binding ;
Cellular component	hemoglobin complex ; cytosol ; blood microparticle ; haptoglobin-hemoglobin complex ;
Biological process	oxygen transport ; blood coagulation ; transport ; hydrogen peroxide catabolic process ; protein heterooligomerization ; cellular oxidant detoxification ;
	Sources:Amigo / QuickGO
Orthologs
	3045
	n/a
	ENSG00000223609
	n/a
	P02042
	n/a
	NM_000519
	n/a
	NP_000510
	n/a
	Wikidata
View/Edit Human

Last updated October 20, 2022

Hemoglobin subunit delta is a protein that in humans is encoded by the HBD gene.^[3]

Function

The delta (HBD) and beta (HBB) genes are normally expressed in the adult: two alpha chains plus two beta chains constitute HbA, which in normal adult life comprises about 97% of the total hemoglobin. Two alpha chains plus two delta chains constitute HbA2, which with HbF comprises the remaining 3% of adult hemoglobin. Five beta-like globin genes are found within a 45 kb cluster on chromosome 11 in the following order: 5' - epsilon – gamma-G – gamma-A – delta – beta - 3'.^[4]

Clinical significance

Mutations in the delta-globin gene are associated with Delta-thalassemia.^[4]

Related Research Articles

Hemoglobinopathy is the medical term for a group of inherited blood disorders and diseases that primarily affect red blood cells. They are single-gene disorders and, in most cases, they are inherited as autosomal co-dominant traits.

Thalassemias are inherited blood disorders characterized by decreased hemoglobin production. Symptoms depend on the type and can vary from none to severe. Often there is mild to severe anemia. Anemia can result in feeling tired and pale skin. There may also be bone problems, an enlarged spleen, yellowish skin, and dark urine. Slow growth may occur in children.

Hemoglobin A (HbA), also known as adult hemoglobin, hemoglobin A1 or α₂β₂, is the most common human hemoglobin tetramer, accounting for over 97% of the total red blood cell hemoglobin. Hemoglobin is an oxygen-binding protein, found in erythrocytes, which transports oxygen from the lungs to the tissues. Hemoglobin A is the most common adult form of hemoglobin and exists as a tetramer containing two alpha subunits and two beta subunits (α2β2). Hemoglobin A2 (HbA2) is a less common adult form of hemoglobin and is composed of two alpha and two delta-globin subunits. This hemoglobin makes up 1-3% of hemoglobin in adults.

Alpha-thalassemia is a form of thalassemia involving the genes HBA1 and HBA2. Thalassemias are a group of inherited blood conditions which result in the impaired production of hemoglobin, the molecule that carries oxygen in the blood. Normal hemoglobin consists of two alpha chains and two beta chains; in alpha-thalassemia, there is a quantitative decrease in the amount of alpha chains, resulting in fewer normal hemoglobin molecules. Furthermore, alpha-thalassemia leads to the production of unstable beta globin molecules which cause increased red blood cell destruction. The degree of impairment is based on which clinical phenotype is present.

Beta thalassemias are a group of inherited blood disorders. They are forms of thalassemia caused by reduced or absent synthesis of the beta chains of hemoglobin that result in variable outcomes ranging from severe anemia to clinically asymptomatic individuals. Global annual incidence is estimated at one in 100,000. Beta thalassemias occur due to malfunctions in the hemoglobin subunit beta or HBB. The severity of the disease depends on the nature of the mutation.

A locus control region (LCR) is a long-range cis-regulatory element that enhances expression of linked genes at distal chromatin sites. It functions in a copy number-dependent manner and is tissue-specific, as seen in the selective expression of β-globin genes in erythroid cells. Expression levels of genes can be modified by the LCR and gene-proximal elements, such as promoters, enhancers, and silencers. The LCR functions by recruiting chromatin-modifying, coactivator, and transcription complexes. Its sequence is conserved in many vertebrates, and conservation of specific sites may suggest importance in function. It has been compared to a super-enhancer as both perform long-range cis regulation via recruitment of the transcription complex.

The human β-globin locus is composed of five genes located on a short region of chromosome 11, responsible for the creation of the beta parts of the oxygen transport protein Haemoglobin. This locus contains not only the beta globin gene but also delta, gamma-A, gamma-G, and epsilon globin. Expression of all of these genes is controlled by single locus control region (LCR), and the genes are differentially expressed throughout development.

Hemoglobin subunit beta is a globin protein, coded for by the HBB gene, which along with alpha globin (HBA), makes up the most common form of haemoglobin in adult humans, hemoglobin A (HbA). It is 147 amino acids long and has a molecular weight of 15,867 Da. Normal adult human HbA is a heterotetramer consisting of two alpha chains and two beta chains.

Hemoglobin variants are mutant forms of hemoglobin in a population, caused by variations in genetics. Some well-known hemoglobin variants such as sickle-cell anemia are responsible for diseases, and are considered hemoglobinopathies. Other variants cause no detectable pathology, and are thus considered non-pathological variants.

Krueppel-like factor 1 is a protein that in humans is encoded by the KLF1 gene. The gene for KLF1 is on the human chromosome 19 and on mouse chromosome 8. Krueppel-like factor 1 is a transcription factor that is necessary for the proper maturation of erythroid cells.

Hemoglobin subunit alpha, Hemoglobin, alpha 1, is a hemoglobin protein that in humans is encoded by the HBA1 gene.

Hemoglobin subunit gamma-2 is a protein that in humans is encoded by the HBG2 gene.

Hemoglobin subunit gamma-1 is a protein that in humans is encoded by the HBG1 gene.

Hemoglobin subunit epsilon is a protein that in humans is encoded by the HBE1 gene.

Hemoglobin subunit zeta is a protein that in humans is encoded by the HBZ gene.

Hemoglobin subunit theta-1 is a protein that in humans is encoded by the HBQ1 gene.

Delta-beta thalassemia is a rare form of thalassemia in which there is a reduced production of hemoglobin subunit delta and hemoglobin subunit beta and raised levels of hemoglobin subunit gamma. It is an autosomal recessive disorder.

Hemoglobin, alpha 2 also known as HBA2 is a gene that in humans codes for the alpha globin chain of hemoglobin.

Mu hemoglobin is a predicted protein encoded in the HBM gene. The mRNA is expressed at moderate levels, but the protein has not been detected by mass spectrometry. The order of genes is: 5' - zeta - pseudozeta - mu - pseudoalpha-1 - alpha-2 - alpha-1 - theta1 - 3'.

<span class="mw-page-title-main">Hemoglobin Lepore syndrome</span> Medical condition

Hemoglobin Lepore syndrome is typically an asymptomatic hemoglobinopathy, which is caused by an autosomal recessive genetic mutation. The Hb Lepore variant, consisting of two normal alpha globin chains (HBA) and two delta-beta globin fusion chains which occurs due to a "crossover" between the delta (HBD) and beta globin (HBB) gene loci during meiosis and was first identified in the Lepore family, an Italian-American family, in 1958. There are three varieties of Hb Lepore, Washington, Baltimore and Hollandia. All three varieties show similar electrophoretic and chromatographic properties and hematological findings bear close resemblance to those of the beta-thalassemia trait; a blood disorder that reduces the production of the iron-containing protein hemoglobin which carries oxygen to cells and which may cause anemia.