HBD จิตร ภูมิศักดิ์ 2020
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Hemoglobin subunit delta is a
protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...
that in
human Humans (''Homo sapiens'') or modern humans are the most common and widespread species of primate, and the last surviving species of the genus ''Homo''. They are Hominidae, great apes characterized by their Prehistory of nakedness and clothing ...
s is encoded by the ''HBD''
gene In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protei ...
.


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 Hemoglobin, alpha 2 also known as ''HBA2'' is a gene that in humans codes for the alpha globin chain of hemoglobin. Function The human alpha globin gene cluster is located on chromosome 16 and spans about 30 kb, including seven alpha like glo ...
, 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 Epsilon (, ; uppercase , lowercase or ; ) is the fifth letter of the Greek alphabet, corresponding phonetically to a mid front unrounded vowel or . In the system of Greek numerals it also has the value five. It was derived from the Phoenic ...
gamma-Ggamma-A – delta –
beta Beta (, ; uppercase , lowercase , or cursive ; or ) is the second letter of the Greek alphabet. In the system of Greek numerals, it has a value of 2. In Ancient Greek, beta represented the voiced bilabial plosive . In Modern Greek, it represe ...
- 3'.


Clinical significance

Mutations in the delta-globin gene are associated with
Delta-thalassemia Delta-beta thalassemia is a rare form of thalassemia in which there is a reduced production of HBD, hemoglobin subunit delta and hemoglobin subunit beta and raised levels of HBG1, hemoglobin subunit gamma. It is an autosomal recessive disorder. Si ...
.


See also

*
Hemoglobin Hemoglobin (haemoglobin, Hb or Hgb) is a protein containing iron that facilitates the transportation of oxygen in red blood cells. Almost all vertebrates contain hemoglobin, with the sole exception of the fish family Channichthyidae. Hemoglobin ...
*
Human β-globin locus The human β-globin locus is a cluster of genes located on chromosome 11. It is responsible for creating the β-chains found in hemoglobin. This cluster consists of 5 genes: ϵ, Gγ, Aγ, δ, and β genes, that respective order downstream. These gen ...
*
Thalassemia Thalassemias are a group of Genetic disorder, inherited blood disorders that manifest as the production of reduced hemoglobin. Symptoms depend on the type of thalassemia and can vary from none to severe, including death. Often there is mild to ...


References


Further reading

* * * Hemoglobins {{protein-stub