HLA-B
Encyclopedia
HLA-B is a human
gene
that provides instructions for making a protein
that plays a critical role in the immune system
. HLA-B is part of a family of genes called the human leukocyte antigen
(HLA) complex. The HLA complex helps the immune system distinguish the body's own proteins from proteins made by foreign invaders such as virus
es and bacteria
.
HLA is the human version of the major histocompatibility complex
(MHC), a gene family that occurs in many species. Genes in this complex are separated into three basic groups: class I, class II, and class III. In humans, the HLA-B gene and two related genes, HLA-A
and HLA-C
, are the major genes in MHC class I.
MHC class I genes provide instructions for making proteins that are present on the surface of almost all cells. On the cell surface, these proteins are bound to protein fragments (peptide
s) that have been exported from within the cell. MHC class I proteins display these peptides to the immune system. If the immune system recognizes the peptides as foreign (such as viral or bacterial peptides), it responds by destroying the infected cell.
The HLA-B gene has many different normal variations, allowing each person's immune system to react to a wide range of foreign invaders. Hundreds of versions (alleles) of HLA-B are known, each of which is given a particular number (such as HLA-B27
). Closely related alleles are categorized together; for example, at least 28 very similar alleles are subtypes of HLA-B27. These subtypes are designated as HLA-B*2701 to HLA-B*2728.
The HLA-B gene is located on the short (p) arm of chromosome 6
at position 21.3, from base pair
31,429,845 to base pair 31,432,923.
|+ Serotypes of HLA-B gene products
|- align = "center"
| antigen > -
Broadantigen
Split antigens
|- align="center"
| B7
B5
B51
B52
|- align="center"
| B8
B12
B44
B45
| B13
B14
B64
| B18
B15
B62
B63
B70
>- align="center"
| B27
B72
B75
B77
>- align="center"
| B35
B16
B38
B39
>- align="center"
| B37
B17
B57
B58
|- align="center"
| B41
B21
B49
B50
| B42
B22
B54
B55
B56
>- align="center"
| B46
B40
B60
B61
>- align="center"
| B47
| B48
| B53
| B59
| B67
| B73
| B78
| B81
| B*82
| B*83
"HLA-" prefix trimmed from serotype names.
Ankylosing spondylitis
: A version of the HLA-B gene called HLA-B27 increases the risk of developing ankylosing spondylitis. It is uncertain how HLA-B27 causes this increased risk. Researchers speculate that HLA-B27 may abnormally display to the immune system peptides that trigger arthritis. Other research suggests that joint inflammation characteristic of this disorder may result from improper folding of the HLA-B27 protein or the presence of abnormal forms of the protein on the cell surface. Although most patients with ankylosing spondylitis have the HLA-B27 variation, many people with this particular variation never develop the disorder. Other genetic and environmental factors are likely to affect the chances of developing ankylosing spondylitis and influence its progression.
HLA-B27 is associated with the spondyloarthropathies, a group of disorders that includes ankylosing spondylitis and other inflammatory joint diseases. Some of these diseases are associated with a common skin condition called psoriasis
or chronic inflammatory bowel disorders (Crohn's disease
and ulcerative colitis
). One of the spondyloarthropathies, reactive arthritis
, is typically triggered by bacterial infections of the gastrointestinal or genital tract. Following an infection, affected individuals may develop arthritis, back pain, and eye inflammation. Like ankylosing spondylitis, many factors probably contribute to the development of reactive arthritis and other spondyloarthropathies.
Other disorders: Several variations of the HLA-B gene are associated with adverse reactions to certain drugs. For example, two specific versions of this gene are related to increased drug sensitivity among the Han Chinese
population. Individuals who have HLA-B*1502 are more likely to experience a severe skin disorder called Stevens–Johnson syndrome in response to carbamazepine
(a drug used to treat seizures). Another version, HLA-B*5801, is associated with an increased risk of severe skin reactions in people treated with allopurinol
(a drug used to treat gout
, which is a form of arthritis caused by uric acid
in the joints).
Among people with human immunodeficiency virus (HIV) infection, a version of HLA-B designated HLA-B*5701 is associated with an extreme sensitivity to abacavir
. This drug is a treatment for HIV-1 that slows the spread of the virus in the body. People with abacavir hypersensitivity often develop a fever, chills, rash, upset stomach, and other symptoms when treated with this drug.
Several other variations of the HLA-B gene appear to play a role in the progression of HIV infection to acquired immunodeficiency syndrome (AIDS
). AIDS is a disease that damages the immune system, preventing it from effectively defending the body against infections. The signs and symptoms of AIDS may not appear until 10 years or more after infection with HIV. Studies suggest that people with HIV infection who have HLA-B27 or HLA-B57 tend to progress more slowly than usual to AIDS. On the other hand, researchers believe that HIV-positive individuals who have HLA-B35 tend to develop the signs and symptoms of AIDS more quickly than usual. Other factors also influence the progression of HIV to AIDS.
Another version of the HLA-B gene, HLA-B53, has been shown to help protect against severe malaria. HLA-B53 is most common in West African populations, where malaria
is a frequent cause of death in children. Researchers suggest that this version of the HLA-B gene may help the immune system respond more effectively to the parasite that causes malaria.
This article incorporates public domain text from The U.S. National Library of Medicine
Human
Humans are the only living species in the Homo genus...
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...
that provides instructions for making 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...
that plays a critical role in the immune system
Immune system
An immune system is a system of biological structures and processes within an organism that protects against disease by identifying and killing pathogens and tumor cells. It detects a wide variety of agents, from viruses to parasitic worms, and needs to distinguish them from the organism's own...
. HLA-B is part of a family of genes called the human leukocyte antigen
Human leukocyte antigen
The human leukocyte antigen system is the name of the major histocompatibility complex in humans. The super locus contains a large number of genes related to immune system function in humans. This group of genes resides on chromosome 6, and encodes cell-surface antigen-presenting proteins and...
(HLA) complex. The HLA complex helps the immune system distinguish the body's own proteins from proteins made by foreign invaders such as virus
Virus
A virus is a small infectious agent that can replicate only inside the living cells of organisms. Viruses infect all types of organisms, from animals and plants to bacteria and archaea...
es and bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
.
HLA is the human version of the major histocompatibility complex
Major histocompatibility complex
Major histocompatibility complex is a cell surface molecule encoded by a large gene family in all vertebrates. MHC molecules mediate interactions of leukocytes, also called white blood cells , which are immune cells, with other leukocytes or body cells...
(MHC), a gene family that occurs in many species. Genes in this complex are separated into three basic groups: class I, class II, and class III. In humans, the HLA-B gene and two related genes, HLA-A
HLA-A
HLA-A are a group of human leukocyte antigens that are encoded by the HLA-A locus on human chromosome 6p. The HLA genes constitute a large subset of the Major histocompatibility complex of humans. HLA-A is a component of certain MHC class I cell surface receptor isoforms that resides on the...
and HLA-C
HLA-C
HLA-C belongs to the MHC class I heavy chain receptors. The C receptor is a heterodimer consisting of a HLA-C mature gene product and β2-microglobulin. The mature C chain is anchored in the membrane...
, are the major genes in MHC class I.
MHC class I genes provide instructions for making proteins that are present on the surface of almost all cells. On the cell surface, these proteins are bound to protein fragments (peptide
Peptide
Peptides are short polymers of amino acid monomers linked by peptide bonds. They are distinguished from proteins on the basis of size, typically containing less than 50 monomer units. The shortest peptides are dipeptides, consisting of two amino acids joined by a single peptide bond...
s) that have been exported from within the cell. MHC class I proteins display these peptides to the immune system. If the immune system recognizes the peptides as foreign (such as viral or bacterial peptides), it responds by destroying the infected cell.
The HLA-B gene has many different normal variations, allowing each person's immune system to react to a wide range of foreign invaders. Hundreds of versions (alleles) of HLA-B are known, each of which is given a particular number (such as HLA-B27
HLA-B27
Human Leukocyte Antigen B27 is a class I surface antigen encoded by the B locus in the major histocompatibility complex on chromosome 6 and presents antigenic peptides to T cells...
). Closely related alleles are categorized together; for example, at least 28 very similar alleles are subtypes of HLA-B27. These subtypes are designated as HLA-B*2701 to HLA-B*2728.
The HLA-B gene is located on the short (p) arm of chromosome 6
Chromosome 6 (human)
Chromosome 6 is one of the 23 pairs of chromosomes in humans. People normally have two copies of this chromosome. Chromosome 6 spans more than 170 million base pairs and represents between 5.5 and 6% of the total DNA in cells...
at position 21.3, from base pair
Base pair
In molecular biology and genetics, the linking between two nitrogenous bases on opposite complementary DNA or certain types of RNA strands that are connected via hydrogen bonds is called a base pair...
31,429,845 to base pair 31,432,923.
Related conditions
|- align = "center"
| antigen >
|- align="center"
| B7
HLA-B7
HLA-B7 is an HLA-B serotype. The serotype identifies the more common HLA-B*07 gene products. B7, previously HL-A7, was one of the first 'HL-A' antigens recognized, largely because of the frequency of B*0702 in Northern and Western Europe and the United States...
HLA-B5
HLA-B5 is an HLA-B serotype. B5 is a broad antigen serotype that recognizes the B51 and B52 split antigen serotypes.-Serotype:...
HLA-B51
HLA-B51 is an HLA-B serotype. The serotype identifies the more common HLA-B*51 gene products.B51 is a split antigen of the broad antigen B5, and is a sister serotype of B52. There are a large number of alleles within the B*51 allele group...
HLA-B52
HLA-B52 is an HLA-B serotype. The serotype identifies the more common HLA-B*52 gene products.B52 is a split antigen of the broad antigen B5, and is a sister type of B51...
|- align="center"
| B8
HLA-B8
HLA-B8 is an HLA-B serotype. The serotype identifies the HLA-B*08 gene products. HLA-B8, previously known as HL-A8 was one of the first identified of the HLA antigens. It coined the "Super B8" haplotype, also called the ancestral European haplotype because of its common occurrence in Europe,...
HLA-B12
HLA-B12 is an HLA - B serotype. B12 is a broad antigen serotype that recognizes the B44 and B45 split antigen serotypes....
HLA-B44
HLA-B44 is an HLA-B serotype. The serotype identifies the B*44 gene-allele protein products of HLA-B.B44 is a split antigen of the broad antigen B12, and is a sister type of B45.-Serotype:-Disease:...
HLA-B45
HLA-B45 is an HLA-B serotype. The serotype identifies the B*45 gene-allele protein products of HLA-B.B45 is a split antigen of the broad antigen B12, and is a sister type of B44.-Serotype:-Alleles:...
| B13
HLA-B13
HLA-B13 is an HLA-B serotype. The serotype identifies the more common HLA-B*13 gene products. -Serotype:-Allele frequencies:...
HLA-B14
HLA-B14 is a HLA-B serotype. The serotype identifies the B*45 gene-allele protein products of HLA-B.B14 is a broad antigen composed to two, B64 and B65, split antigens...
| B18
HLA-B18
HLA-B18 is an HLA-B serotype. The serotype identifies the more common HLA-B*18 gene products. B*1801, the most common allele is at highest frequencies in Northern Italy and the Balkans, a peak frequency distribution it shares with B*3501.-Serotype:-Allele frequencies:...
HLA-B15
HLA-B15 is an HLA-B serotype. The serotype identifies the B*15 gene-allele protein products of HLA-B.B15 is a broad antigen can be subdivided into several split antigens that are often used in characterization. These are B62, B63, B70, B71, B72, B75, B76, B77...
HLA-B62
HLA-B62 is an HLA-B serotype. The serotype identifies certain B*15 gene-allele protein products of HLA-B.B62 is largest of many split antigens of the broad antigen, B15. B62 best identifies the B*1501, B*1504, B*1507, and B*1525 allele products....
HLA-B63
HLA-B63 is an HLA-B serotype. The serotype identifies certain B*15 gene-allele protein products of HLA-B.B63 is one of many split antigens of the broad antigen, B15. B63 identifies the B*1516 and B*1517 allele products.-Serotype:-Alleles:...
HLA-B70
HLA-B70 is an HLA-B serotype. The serotype identifies certain B*15 gene-allele protein products of HLA-B.B70 is one of many split antigens of the broad antigen, B15.-Serotype:-Alleles:...
>- align="center"
| B27
HLA-B27
Human Leukocyte Antigen B27 is a class I surface antigen encoded by the B locus in the major histocompatibility complex on chromosome 6 and presents antigenic peptides to T cells...
HLA-B75
HLA-B75 is an HLA-B serotype. The serotype identifies certain B*15 gene-allele protein products of HLA-B.B75 is one of many split antigens of the broad antigen, B15...
HLA-B77
HLA-B77 is an HLA-B serotype. The serotype identifies certain B*15 gene-allele protein products of HLA-B.B77 is a split antigen of the broad antigen B15.-Serotype:...
>- align="center"
| B35
HLA-B35
HLA-B35 is an HLA-B serotype. The serotype identifies the more common HLA-B*35 gene products.B35 is one of the largest B serotype groups, it currently has 97 known nucleotide variants and 86 polypeptide isoforms. -Serotype:...
HLA-B16
HLA-B16 is an HLA - B serotype. B16 is a broad antigen serotype that recognizes the B38 and B39 split antigen serotypes....
HLA-B38
HLA-B38 is an HLA-B serotype. The serotype identifies the B*38 allele products of the HLA-B gene-locus.B38 is a split antigen of the broad antigen B16, and is a sister type of B39...
HLA-B39
HLA-B39 is an HLA-B serotype. The serotype identifies the more common HLA-B*39 gene products.B39 is a split antigen of the broad antigen B16, and is a sister type of B38. B39 is most commonly found on the west pacific rim, in Japan and highest frequency in the new world...
>- align="center"
| B37
HLA-B37
HLA-B37 is an HLA-B serotype. The serotype identifies the more common HLA-B*37 gene products. -Serotype:-Alleles:...
HLA-B17
HLA-B17 is an HLA - B serotype. B17 is a broad antigen serotype that recognizes the B57 and B58 split antigen serotypes. B17 is still encountered in the current literature, although most studies now use B57/B58 or gene typing designators. Both serotypes are involved in slightly different...
HLA-B57
HLA-B57 is an HLA-B serotype. B57 is a split antigen from the B17 broad antigen, the sister serotype B58. The serotype identifies the more common HLA-B*58 gene products...
HLA-B58
HLA-B58 is an HLA-B serotype. B58 is a split antigen from the B17 broad antigen, the sister serotype B57. The serotype identifies the more common HLA-B*58 gene products...
|- align="center"
| B41
HLA-B41
HLA-B41 is an HLA-B serotype. The serotype identifies HLA-B*4101, *4102, *4103 gene products. -Serotype:-Allele frequencies:...
HLA-B21
HLA-B21 is an HLA - B serotype. B21 is a broad antigen serotype that recognizes the B49 and B50 split antigen serotypes....
HLA-B49
HLA-B49 is an HLA-B serotype. B49 is a split antigen from the B21 broad antigen, the sister serotype B50. The serotype identifies the more common HLA-B*50 gene products. -Serotype:...
HLA-B50
HLA-B50 is an HLA-B serotype. B50 is a split antigen from the B21 broad antigen, the sister serotype B49. The serotype identifies the more common HLA-B*50 gene products. -Serotype:...
| B42
HLA-B42
HLA-B42 is an HLA-B serotype. The serotype identifies the HLA-B*4201 and *4202 gene products. HLA-B*4201 is common in Central Africa. -Serotype:...
HLA-B22
HLA-B22 is an HLA - B serotype. B22 is a broad antigen serotype that recognizes the B54, B55, and B56 split antigen serotypes....
HLA-B54
HLA-B54 is an HLA-B serotype. B54 is a split antigen from the B22 broad antigen, sister serotypes are B55 and B56. The serotype identifies the more common HLA-B*55 gene products.-Serotype:-Allele distribution:...
HLA-B55
HLA-B55 is an HLA-B serotype. B55 is a split antigen from the B22 broad antigen, sister serotypes are B54 and B56. The serotype identifies the more common HLA-B*55 gene products. -Serotype:...
HLA-B56
HLA-B56 is an HLA-B serotype. B56 is a split antigen from the B22 broad antigen, sister serotypes are B54 and B55. The serotype identifies the more common HLA-B*56 gene products. -Serotype:...
>- align="center"
| B46
HLA-B46
HLA-B46 is an HLA-B serotype. The serotype identifies the gene products of HLA-B*4601 allele.B*4601 resulted from a rare, interlocus, gene conversion between B62, probably B*1501, and a HLA-C allele. B*4601 is the most common HLA-B allele that does not have an origin within Africa, and estimated...
HLA-B40
HLA-B40 is an HLA - B serotype. B40 is composed of the B60 and B61 split antigen serotypes-Serotype:B*4005 is poorly recognized by B40, B60, or B61....
HLA-B60
HLA-B60 is an HLA - B serotype. B60 is a split antigen serotype that recognizes certain B40 serotypes.-Serotype:...
HLA-B61
HLA-B61 is an HLA - B serotype. B61 is a split antigen serotype that recognizes certain B40 serotypes.-Serotype:...
>- align="center"
| B47
HLA-B47
HLA-B47 is an HLA-B serotype. The serotype identifies the HLA-B*47 gene products . Comparison of B47 nucleotide sequence with other HLA-B sequences shows a segment of 228 bp identical with B44 in the alpha 1 domain and a segment of 218 bp identical with B27 in the alpha 2 domain, but only a 91 bp...
| B48
HLA-B48
HLA-B48 is an HLA-B serotype. The serotype identifies the more common HLA-B*48 gene products. B48 is most common along the West Pacific Rim, Americas indigeonous peoples and Northern Eurasians...
| B53
HLA-B53
HLA-B53 is an HLA-B serotype. The serotype identifies the more common HLA-B*53 gene products. The B53 sequence is identical to B35 but short sequence specifies a Bw4 rather than a Bw6 motif , indicating B53 is a recent product of gene conversion. This suggests an origin for HLA-B53 involving a...
| B59
HLA-B59
HLA-B59 is an HLA-B serotype. The serotype identifies the more common HLA-B*## gene products. B59 is a hybrid between B*55 and B*51. B59 is more common in Japan, Korea, N. China and Mongolia. -Serotype:...
| B67
HLA-B67
HLA-B67 is an HLA-B serotype. The serotype identifies the more common HLA-B*67 gene products. B67 is region specific recombinant haplotype formed by the gene conversion of B*39, an allele common along the Northwest Pacific Rim , and B7, B22, or B27. -Serotype:-By allele:...
| B73
HLA-B73
HLA-B73 is an HLA-B serotype. The serotype identifies the HLA-B*7301 gene product. Part of B*7301 is similar to the HLA-B22 family, however part resembles the domains seen in other apes. B73 is more common in Western Indian Ocean, Mediterranean and Africa. -Serotype:-B*7301 frequencies:...
| B78
HLA-B78
HLA-B78 is an HLA-B serotype. The serotype identifies the more common HLA-B*78 gene products. B78 is more common in West and North Africa, but is also scattered at low frequencies in parts of Asia....
| B81
HLA-B81
HLA-B81 is an HLA-B serotype. The serotype identifies the HLA-B*8101 and B*8102 gene products. B81 is more common in Subsaharan Africa. While there is a B81 serotype, serotyping of B81 is poor when simultaneously tested with anti-B7 or B48 antibodies...
| B*82
| B*83
Ankylosing spondylitis
Ankylosing spondylitis
Ankylosing spondylitis , previously known as Bekhterev's disease, Bekhterev syndrome, and Marie-Strümpell disease is a chronic inflammatory disease of the axial skeleton with variable involvement of peripheral joints and nonarticular structures...
: A version of the HLA-B gene called HLA-B27 increases the risk of developing ankylosing spondylitis. It is uncertain how HLA-B27 causes this increased risk. Researchers speculate that HLA-B27 may abnormally display to the immune system peptides that trigger arthritis. Other research suggests that joint inflammation characteristic of this disorder may result from improper folding of the HLA-B27 protein or the presence of abnormal forms of the protein on the cell surface. Although most patients with ankylosing spondylitis have the HLA-B27 variation, many people with this particular variation never develop the disorder. Other genetic and environmental factors are likely to affect the chances of developing ankylosing spondylitis and influence its progression.
HLA-B27 is associated with the spondyloarthropathies, a group of disorders that includes ankylosing spondylitis and other inflammatory joint diseases. Some of these diseases are associated with a common skin condition called psoriasis
Psoriasis
Psoriasis is an autoimmune disease that appears on the skin. It occurs when the immune system mistakes the skin cells as a pathogen, and sends out faulty signals that speed up the growth cycle of skin cells. Psoriasis is not contagious. However, psoriasis has been linked to an increased risk of...
or chronic inflammatory bowel disorders (Crohn's disease
Crohn's disease
Crohn's disease, also known as regional enteritis, is a type of inflammatory bowel disease that may affect any part of the gastrointestinal tract from mouth to anus, causing a wide variety of symptoms...
and ulcerative colitis
Ulcerative colitis
Ulcerative colitis is a form of inflammatory bowel disease . Ulcerative colitis is a form of colitis, a disease of the colon , that includes characteristic ulcers, or open sores. The main symptom of active disease is usually constant diarrhea mixed with blood, of gradual onset...
). One of the spondyloarthropathies, reactive arthritis
Reactive arthritis
Reactive arthritis , is classified as an autoimmune condition that develops in response to an infection in another part of the body. Coming into contact with bacteria and developing an infection can trigger the disease. Reiter's syndrome has symptoms similar to various other conditions collectively...
, is typically triggered by bacterial infections of the gastrointestinal or genital tract. Following an infection, affected individuals may develop arthritis, back pain, and eye inflammation. Like ankylosing spondylitis, many factors probably contribute to the development of reactive arthritis and other spondyloarthropathies.
Other disorders: Several variations of the HLA-B gene are associated with adverse reactions to certain drugs. For example, two specific versions of this gene are related to increased drug sensitivity among the Han Chinese
Han Chinese
Han Chinese are an ethnic group native to China and are the largest single ethnic group in the world.Han Chinese constitute about 92% of the population of the People's Republic of China , 98% of the population of the Republic of China , 78% of the population of Singapore, and about 20% of the...
population. Individuals who have HLA-B*1502 are more likely to experience a severe skin disorder called Stevens–Johnson syndrome in response to carbamazepine
Carbamazepine
Carbamazepine is an anticonvulsant and mood-stabilizing drug used primarily in the treatment of epilepsy and bipolar disorder, as well as trigeminal neuralgia...
(a drug used to treat seizures). Another version, HLA-B*5801, is associated with an increased risk of severe skin reactions in people treated with allopurinol
Allopurinol
Allopurinol is a drug used primarily to treat hyperuricemia and its complications, including chronic gout.- Mechanism of action :...
(a drug used to treat gout
Gout
Gout is a medical condition usually characterized by recurrent attacks of acute inflammatory arthritis—a red, tender, hot, swollen joint. The metatarsal-phalangeal joint at the base of the big toe is the most commonly affected . However, it may also present as tophi, kidney stones, or urate...
, which is a form of arthritis caused by uric acid
Uric acid
Uric acid is a heterocyclic compound of carbon, nitrogen, oxygen, and hydrogen with the formula C5H4N4O3. It forms ions and salts known as urates and acid urates such as ammonium acid urate. Uric acid is created when the body breaks down purine nucleotides. High blood concentrations of uric acid...
in the joints).
Among people with human immunodeficiency virus (HIV) infection, a version of HLA-B designated HLA-B*5701 is associated with an extreme sensitivity to abacavir
Abacavir
Abacavir is a nucleoside analog reverse transcriptase inhibitor used to treat HIV and AIDS. It is available under the trade name Ziagen and in the combination formulations Trizivir and Kivexa/Epzicom...
. This drug is a treatment for HIV-1 that slows the spread of the virus in the body. People with abacavir hypersensitivity often develop a fever, chills, rash, upset stomach, and other symptoms when treated with this drug.
Several other variations of the HLA-B gene appear to play a role in the progression of HIV infection to acquired immunodeficiency syndrome (AIDS
AIDS
Acquired immune deficiency syndrome or acquired immunodeficiency syndrome is a disease of the human immune system caused by the human immunodeficiency virus...
). AIDS is a disease that damages the immune system, preventing it from effectively defending the body against infections. The signs and symptoms of AIDS may not appear until 10 years or more after infection with HIV. Studies suggest that people with HIV infection who have HLA-B27 or HLA-B57 tend to progress more slowly than usual to AIDS. On the other hand, researchers believe that HIV-positive individuals who have HLA-B35 tend to develop the signs and symptoms of AIDS more quickly than usual. Other factors also influence the progression of HIV to AIDS.
Another version of the HLA-B gene, HLA-B53, has been shown to help protect against severe malaria. HLA-B53 is most common in West African populations, where malaria
Malaria
Malaria is a mosquito-borne infectious disease of humans and other animals caused by eukaryotic protists of the genus Plasmodium. The disease results from the multiplication of Plasmodium parasites within red blood cells, causing symptoms that typically include fever and headache, in severe cases...
is a frequent cause of death in children. Researchers suggest that this version of the HLA-B gene may help the immune system respond more effectively to the parasite that causes malaria.
Further reading
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