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| ===MHC Polymorphism In People=== | | ===MHC Polymorphism In People=== |
− | * There are three types (loci) of MHC class I molecules known as human leukocyte antigen (HLA)- A, B, and C | + | * There are three types (loci) of MHC class I molecules known as human leukocyte antigen (HLA) - A, B, and C |
| * Equally there are three loci of MHC class II molecules - HLAs DP, DQ and DR | | * Equally there are three loci of MHC class II molecules - HLAs DP, DQ and DR |
| In the entire human population there are only approximately 50 different variants (alleles) at each MHC class I and class II locus. | | In the entire human population there are only approximately 50 different variants (alleles) at each MHC class I and class II locus. |
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| The variation within MHC class I is entirely based on the class I heavy chain (the β2m is invariant). The variation within MHC class II is mainly within the β chains. Every individual has two alleles at each MHC locus inherited one from each parent. Any individual will therefore express two variants at most at each locus. | | The variation within MHC class I is entirely based on the class I heavy chain (the β2m is invariant). The variation within MHC class II is mainly within the β chains. Every individual has two alleles at each MHC locus inherited one from each parent. Any individual will therefore express two variants at most at each locus. |
| This gives a maximum variability for an individual of: | | This gives a maximum variability for an individual of: |
− | * 6 different variants of MHC class I (2 each of HLA- A, B and C) | + | * 6 different variants of MHC class I (2 each of HLA - A, B and C) |
− | * 6 different variants of MHC class II (2 each of HLA- DP, DQ and DR) | + | * 6 different variants of MHC class II (2 each of HLA - DP, DQ and DR) |
| Many animal species have fewer loci than the human e.g. ruminants have no MHC class II DP. | | Many animal species have fewer loci than the human e.g. ruminants have no MHC class II DP. |
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