HLA A1-B8 haplotype
| Multi-gene haplotype, human | |||
|---|---|---|---|
 |
|||
| HLA region on chromosome 6 | |||
| Class I, A1-Cw7-B8 | |||
| Nicknames | "HL A1,8; HL A1,A8; HLA A1-B8; HLA A*01-B*08, HLA A*01:01-B*08:01" |
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| Loci | Gene | Allele | Serotype |
| HLA-F to HLA-A |
HLA-F | *0101 | - |
| HLA-G | *0101 | - | |
| HLA-A | *0101 | A1 | |
| HLA-E | HLA-E | *0101 | - |
| Cw-B | HLA-C | *0701 | Cw7 |
| HLA-B | *0801 | B8 | |
| Nodes | |||
| PopulationMaxima | Freq.Max | ||
| Western Ireland | >15.0% | ||
| Size and location | |||
| Genes | Location | size (kbps) | |
| - | 6 | 6p21.3 | 1400 |
HLA A1-B8 (Also:HL A1,8; HL A1,A8; HLA A1-Cw7-B8; HLA A*01-B*08, HLA A*0101-B*0801, HLA A*0101-Cw*0701-B*0801; HLA A*01:01-C*07:01-B*08:01) is a multigene that covers the MHC Class I region of the human on chromosome 6. A multigene haplotype is set of inherited covering several genes, or gene-alleles; common multigene haplotypes are generally the result of identity by descent from a common ancestor (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.
The haplotype can be written in an extended form covering the major histocompatibility loci as follows:
HLA A*01:01 : Cw*07:01 : B*08:01
However, there are many other gene-alleles within the haplotype. In Europe A1-B8 is found, generally as part of the HLA A1-B8-DR3-DQ2 haplotype. This haplotype is 4.7 million nucleotides in length and the second longest haplotype identified within the human genome. In Africa A1-B8 and India A1-B8 is associated with other genes and other variants of A*01 and B*08
Philosophically, A1-B8 is more than just two gene-alleles. These gene-alleles are markers for a haplotype, a stretch of chromosome 6 that contains many gene alleles. In its natural history this haplotype underwent some atypical selection, at the end of the period of evolution it became the predominant haplotypes in North/Western European ancestors. Today however the collection of genes is associated with increased incidences of certain diseases. Despite the fact that the associations have been known almost as long as A1 and "A8" were known, the role of factors affecting disease are still not clear.
A1-B8 serotype was associated with a number of diseases as "HL-A"' antigens were first being described. Among these were coeliac disease, autoimmune active chronic hepatitis, myasthenia gravis, Adrenocortical hyperfunction-Cushing's syndrome, primary biliary cirrhosis.
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