HLA B7-DR15-DQ6 is a multigene

haplotype A haplotype ( haploid genotype) is a group of alleles in an organism that are inherited together from a single parent. Many organisms contain genetic material ( DNA) which is inherited from two parents. Normally these organisms have their DNA or ...

that covers a majority of the human

major histocompatibility complex The major histocompatibility complex (MHC) is a large locus on vertebrate DNA containing a set of closely linked polymorphic genes that code for cell surface proteins essential for the adaptive immune system. These cell surface proteins are calle ...

chromosome 6 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 (the building material of DNA) and represents between 5.5 and 6% of the total ...

. A multigene haplotype is set of inherited

alleles An allele (, ; ; modern formation from Greek ἄλλος ''állos'', "other") is a variation of the same sequence of nucleotides at the same place on a long DNA molecule, as described in leading textbooks on genetics and evolution. ::"The chro ...

covering several genes, or gene-alleles, common multigene haplotypes are generally the result of descent by common ancestry (share a recent common ancestor for that segment of the chromosome). Chromosomal recombination fragments multigene haplotypes as the distance to that ancestor increases in number of generations. HLA B7-DR15-DQ6 is a representation(by

serotype A serotype or serovar is a distinct variation within a species of bacteria or virus or among immune cells of different individuals. These microorganisms, viruses, or cells are classified together based on their surface antigens, allowing the epi ...

) of a common HLA

found in Western Eurasia. The haplotype can be written in an extended form covering the major histocompatibility loci as follows:

HLA Cw*0702 : B*0702 : DRB1*1501 : DQA1*0102 : DQB1*0602

The older literature may describe this haplotype in two different ways. One B7-DR2-DQ6 derives from the fact that DR15 is a split antigen of the DR2 broad antigen serotype. The other B7-DR2-DQ1 stems from the fact that DQ1 is an alpha chain serotype that is now covered by the beta chain type DQ5 and DQ6 (DQ1 pairs with DQ5 and DQ6 by cis-haplotype pairing). There are two major subhaplotypes one that is preceded on its telomeric side by HLA A*0301 and the other by HLA A*0201. The A*0301 bearing haplotype (HLA A3-B7-DR15-DQ6) is described as the longest known multgene haplotype in humans.

HLA A2-B7-DR15-DQ6

The appendation of the B7::DQ6 haplotype creates the A2-B7::DQ6 haplotype. This haplotype if found often in Northern Spain, Switzerland, Netherlands.

HLA A*0201Cw*0702 : B*0702 : DRB1*1501 : DQA1*0102 : DQB1*0602

HLA A3-B7-DR15-DQ6

The gene-allele representation of the haplotype is:

HLA A*0301Cw*0702 : B*0702 : DRB1*1501 : DQA1*0102 : DQB1*0602

This is considered now the longest of the widely distributed ancestral haplotypes, its length is 4.8 million nucleotides and extends from TRIM27 gene . . . .The haplotype is nodal in Ireland but is also at high frequency in Switzerland, it has a subnode in the Pasiegos of northern Spain. There is some variance in the distribution of A3::DQ6 relative to A1::DQ2 in that there is more of a bias toward central and eastern Europe. Parts of the haplotype are spread into East Asia and even appear within the New world's indigenous populations. DR15:DQ6 frequencies peak in central Asia, and it is suspect that this may be a point of Eurasian spread westward into Europe. While there are some diseases associated with the haplotype, the frequency of association is less compared to A1::B8.

Disease Associations

HLA B7-DR15-DQ6 was found to have an association with postmenopausal

osteoporosis Osteoporosis is a systemic skeletal disorder characterized by low bone mass, micro-architectural deterioration of bone tissue leading to bone fragility, and consequent increase in fracture risk. It is the most common reason for a broken bone ...

in a

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

population. DR2 (15 or 16) -DQ6.2 has been found to associate with (idiopathic)

narcolepsy Narcolepsy is a long-term neurological disorder that involves a decreased ability to regulate sleep–wake cycles. Symptoms often include periods of excessive daytime sleepiness and brief involuntary sleep episodes. About 70% of those affec ...

cataplexy Cataplexy is a sudden and transient episode of muscle weakness accompanied by full conscious awareness, typically triggered by emotions such as laughing, crying, or terror. Cataplexy affects approximately 70% of people who have narcolepsy, and is ...

Hypocretin Orexin (), also known as hypocretin, is a neuropeptide that regulates arousal, wakefulness, and appetite. The most common form of narcolepsy, type 1, in which the individual experiences brief losses of muscle tone ("drop attacks" or cataplexy), ...

ligand deficiency in the brain and

cerebrospinal fluid Cerebrospinal fluid (CSF) is a clear, colorless body fluid found within the tissue that surrounds the brain and spinal cord of all vertebrates. CSF is produced by specialised ependymal cells in the choroid plexus of the ventricles of the bra ...

is also link to narcolepsy-cataplexy. DR15-DQ6 also shows an association with factors (including a genetic factor on

chromosome 12 Chromosome 12 is one of the 23 pairs of chromosomes in humans. People normally have two copies of this chromosome. Chromosome 12 spans about 133 million base pairs (the building material of DNA) and represents between 4 and 4.5 percent of the to ...

p12) involved in familial

multiple sclerosis Multiple (cerebral) sclerosis (MS), also known as encephalomyelitis disseminata or disseminated sclerosis, is the most common demyelinating disease, in which the insulating covers of nerve cells in the brain and spinal cord are damaged. This d ...

DR15-DQ6 is strongly associated with the development of choroidal neovascular lesions in presumed ocular

histoplasmosis Histoplasmosis is a fungal infection caused by ''Histoplasma capsulatum''. Symptoms of this infection vary greatly, but the disease affects primarily the lungs. Occasionally, other organs are affected; called disseminated histoplasmosis, it can ...

syndrome. The DR15-DQ6 haplotype may afford some greater protection against the progression of

HIV The human immunodeficiency viruses (HIV) are two species of ''Lentivirus'' (a subgroup of retrovirus) that infect humans. Over time, they cause acquired immunodeficiency syndrome (AIDS), a condition in which progressive failure of the immune ...

. However, the haplotype is a risk factor in

cervical cancer Cervical cancer is a cancer arising from the cervix. It is due to the abnormal growth of cells that have the ability to invade or spread to other parts of the body. Early on, typically no symptoms are seen. Later symptoms may include abnormal ...

References

{{DEFAULTSORT:Hla B7-Dr15-Dq6 Human MHC haplogroups Human MHC mediated diseases