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  • 1
    ISSN: 1600-065X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Summary: The evolutionary relationships among the MHC class II DRB4, DRB5 and DRB6 loci as well as the allelic lineages and alleles of the DRB1 locus were studied based on intron 1 and Intron 2 sequences from humans, chimpanzee (Pan troglodytes). bonobo (Pan paniscus) and gorilla (Gorilla gorilla). The phylogenetic trees for these sequences indicate that most of the DRB 1 allelic lineages predate the separation of the hominoid species studied, consistent with previous analysis of the coding sequences of these lineages. However, the intron sequence variation among alleles within DRB1 allelic lineages is very limited, consistent with the notion that the majority of the contemporary alleles have been generated within the last 250,000 years. The clustering of the DRB1 allelic lineages *08 and *12 with *03 supports a common ancestry for the DR8 and DR52 haplotypes. Similarly, the clustering of DRB1 allelic lineages *15 and *01 with the DRB3 locus is consistent with a common ancestry for the DR1 and DR51 haplotypes. Two cases of recombination around the second exon were observed: 1) the HLA-DRB6 locus appears to have been generated through a recombination between a DRB5 allele and an ancestral DRB6 allele, and 2) the gorilla sequence Gogo-DRB1*03 appears to have been generated through a recombination between the DRB3 locus and an allele from the DRB1*03 allelic lineage. The nucleotide substitution rate of DRB introns was estimated to 0.85–1.63 × 10-9 per site per year, based on comparisons between the most closely related sequences from different hominoid species. This estimate is similar to the substitution rate for other intronic regions of the primate genome.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature genetics 18 (1998), S. 237-242 
    ISSN: 1546-1718
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Medicine
    Notes: [Auszug] The HLA class I and class II loci are the most highly polymorphic coding regions in the human genome. Based on the similarity of the coding sequences of alleles between species, it has been claimed that the HLA polymorphism is ancient and predates the separation of human (Homo) and chimpanzee ...
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Storey and co-workers claim that there is an association between a common variant of the p53 tumour-suppressor gene and the development of invasive cervical carcinoma. Here we present evidence to refute this, based on a reassessment of the importance of the polymorphism at codon 72 in ...
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-1211
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Cotton-top tamarins (Saguinus oedipus) in captivity are unusual in that they exhibit low levels of polymorphism and allelic diversity at the major histocompatibility complex (Mhc) class I loci. Since the polymorphism has previously only been examined in captive tamarins, we analyzed the Mhc class I alleles of a population of wild tamarins. These wild tamarins, like their captive counterparts, exhibited limited class I polymorphism. We also assessed the levels of polymorphism and allelic diversity at the Mhc class II DQA1, DQB1, DQB2, and the DRB loci in captive populations of cotton-top tamarins. In contrast to the extensive polymorphism in Old World monkeys, only two alleles were detected at each of DQA1 and DQB1. Also, the DQB2 locus was monomorphic and conserved between New and Old World monkeys. Sequences derived from four putative DRB loci were obtained, and extensive polymorphism was found at all four loci. Phylogenetic analysis did not indicate that any of the tamarin DRB loci, with the possible exception of Saoe-DRB3, were orthologous to the human DRB loci. At three of the DRB loci (Saoe-DRB11, Saoe-DRB * W12, Saoe-DRB * W22), the number of nonsynonymous changes was higher than the number of synonymous changes in the putative antigen recognition sites, indicative of positive selection. We found no support for a restriction on the polymorphism at the cotton-top tamarin class II loci. However, the allelic diversity at some of the Saoe-DRB loci is more limited than for the HLA-DRB1, consistent with a restriction imposed by the bone marrow-chimerical lifestyle.
    Type of Medium: Electronic Resource
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