Biomaterial Database

Polymorphism of human Ia antigens: gene conversion between two DR beta loci results in a new HLA-D/DR specificity. 1986

J Gorski, and B Mach

The polymorphic HLA-DR beta-chains are encoded within the human major histocompatibility complex (MHC) by multiple loci resulting from gene duplications. Certain DR haplotypes can be grouped into families based on shared structural factors. We have studied the molecular basis of HLA-DR polymorphism within such a group which includes the haplotypes DR3, DR5 and DRw6. Molecular mapping of the DR beta-chain region allows true allelic comparisons of the two expressed DR beta-chain loci, DR beta I and DR beta III. At the more polymorphic locus, DR beta I, the allelic differences are clustered and may result from gene conversion events over very short distances. The gene encoding the HLA-DR3/Dw3 specificity has been generated by a gene conversion involving the DR beta I and the DR beta III loci of the HLA-DRw6/Dw18 haplotype, as recipient and donor gene, respectively. Based on which allele is found at DR beta III, the less polymorphic locus, two groups of haplotypes can be defined: DRw52a and DRw52b. The generation of HLA-DR polymorphism within the DRw52 supertypic group can thus be accounted for by a succession of gene duplication, divergence and gene conversion.

UI	MeSH Term	Description	Entries
D011110	Polymorphism, Genetic	The regular and simultaneous occurrence in a single interbreeding population of two or more discontinuous genotypes. The concept includes differences in genotypes ranging in size from a single nucleotide site (POLYMORPHISM, SINGLE NUCLEOTIDE) to large nucleotide sequences visible at a chromosomal level.	Gene Polymorphism,Genetic Polymorphism,Polymorphism (Genetics),Genetic Polymorphisms,Gene Polymorphisms,Polymorphism, Gene,Polymorphisms (Genetics),Polymorphisms, Gene,Polymorphisms, Genetic
D002874	Chromosome Mapping	Any method used for determining the location of and relative distances between genes on a chromosome.	Gene Mapping,Linkage Mapping,Genome Mapping,Chromosome Mappings,Gene Mappings,Genome Mappings,Linkage Mappings,Mapping, Chromosome,Mapping, Gene,Mapping, Genome,Mapping, Linkage,Mappings, Chromosome,Mappings, Gene,Mappings, Genome,Mappings, Linkage
D005785	Gene Conversion	The asymmetrical segregation of genes during replication which leads to the production of non-reciprocal recombinant strands and the apparent conversion of one allele into another. Thus, e.g., the meiotic products of an Aa individual may be AAAa or aaaA instead of AAaa, i.e., the A allele has been converted into the a allele or vice versa.	Polar Recombination,Polaron,Conversion, Gene,Conversions, Gene,Gene Conversions,Polar Recombinations,Polarons,Recombination, Polar,Recombinations, Polar
D006238	Haploidy	The chromosomal constitution of cells, in which each type of CHROMOSOME is represented once. Symbol: N.	Haploid,Haploid Cell,Cell, Haploid,Cells, Haploid,Haploid Cells,Haploidies,Haploids
D006684	HLA-DR Antigens	A subclass of HLA-D antigens that consist of alpha and beta chains. The inheritance of HLA-DR antigens differs from that of the HLA-DQ ANTIGENS and HLA-DP ANTIGENS.	HLA-DR,Antigens, HLA-DR,HLA DR Antigens
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000483	Alleles	Variant forms of the same gene, occupying the same locus on homologous CHROMOSOMES, and governing the variants in production of the same gene product.	Allelomorphs,Allele,Allelomorph
D000949	Histocompatibility Antigens Class II	Large, transmembrane, non-covalently linked glycoproteins (alpha and beta). Both chains can be polymorphic although there is more structural variation in the beta chains. The class II antigens in humans are called HLA-D ANTIGENS and are coded by a gene on chromosome 6. In mice, two genes named IA and IE on chromosome 17 code for the H-2 antigens. The antigens are found on B-lymphocytes, macrophages, epidermal cells, and sperm and are thought to mediate the competence of and cellular cooperation in the immune response. The term IA antigens used to refer only to the proteins encoded by the IA genes in the mouse, but is now used as a generic term for any class II histocompatibility antigen.	Antigens, Immune Response,Class II Antigens,Class II Histocompatibility Antigen,Class II Major Histocompatibility Antigen,Ia Antigens,Ia-Like Antigen,Ia-Like Antigens,Immune Response Antigens,Immune-Associated Antigens,Immune-Response-Associated Antigens,MHC Class II Molecule,MHC II Peptide,Class II Antigen,Class II Histocompatibility Antigens,Class II MHC Proteins,Class II Major Histocompatibility Antigens,Class II Major Histocompatibility Molecules,I-A Antigen,I-A-Antigen,IA Antigen,MHC Class II Molecules,MHC II Peptides,MHC-II Molecules,Antigen, Class II,Antigen, I-A,Antigen, IA,Antigen, Ia-Like,Antigens, Class II,Antigens, Ia,Antigens, Ia-Like,Antigens, Immune-Associated,Antigens, Immune-Response-Associated,I A Antigen,II Peptide, MHC,Ia Like Antigen,Ia Like Antigens,Immune Associated Antigens,Immune Response Associated Antigens,MHC II Molecules,Molecules, MHC-II,Peptide, MHC II,Peptides, MHC II
D001483	Base Sequence	The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.	DNA Sequence,Nucleotide Sequence,RNA Sequence,DNA Sequences,Base Sequences,Nucleotide Sequences,RNA Sequences,Sequence, Base,Sequence, DNA,Sequence, Nucleotide,Sequence, RNA,Sequences, Base,Sequences, DNA,Sequences, Nucleotide,Sequences, RNA