Library

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    ISSN: 1432-1432
    Keywords: Key words: HLA-B — TNF — Multicopy gene families
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. The major histocompatibility complex (MHC) contains genes which confer susceptibility to numerous diseases and must be important in primate evolution. In some instances, genes have been mapped to the region between human histocompatibility leukocyte antigen (HLA)-B and tumor necrosis factor (TNF) but precise localization has proven difficult especially since this region is subject to insertions, deletions, and duplications. Utilizing computer similarity searches and coding prediction programs, we have identified several potential coding sequences between HLA-B and TNF. Three of these sequences, PERB11.2, PERB15, and PERB18, are similar to members of multicopy gene families that are located in other regions of the MHC. The identification of numerous fragmented and intact retroelements (L1, Alu, LTR, and THE sequences) flanking the PERB11 and PERB15 genes suggests that these retroelements are involved in the duplication process. The evaluation of candidate genes for disease susceptibility within the MHC is complicated by their similarity to other members of multicopy gene families. The determination of sequence differences within and between species provides a strategy with which to investigate the candidate genes between HLA-B and TNF.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1432-1432
    Keywords: Key words: Polymorphism — Recombination — Ancestral haplotypes — Major histocompatibility complex —Homo sapiens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. The major histocompatibility complex (MHC) consists of polymorphic frozen blocks (PFBs) that are linked to form megabase haplotypes. These blocks consist of polymorphic sequences and define regions where recombination appears to be inhibited. We have been able to show, using a highly polymorphic sequence centromeric of HLA-B (within the beta block), that PFBs are conserved and contain specific insertions/deletions and substitutions that are the same for individuals with the same MHC haplotype but that differ between at least most different haplotypes. A sequence comparison between ethnic-specific haplotypes shows that these sequences have remained stable and predate the formation of these haplotypes. To determine whether the same conserved block has been involved in the generation of multiple haplotypes, we compared the block typing profiles of different ethnic specific haplotypes. Block typing profiles have previously been shown to be identical in individuals with the same MHC haplotype but, generally, to differ between different haplotypes. It was found that some PFBs are common to more than one haplotype, implying a common ancestry. Subsequently, haplotypes have been generated by the shuffling and exchange of these PFBs. The regions between these PFBs appear to permit the recombination sites and therefore could be expected to exhibit either low polymorphism or a localized ``hotspot.''
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 1432-1211
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 1432-1211
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The region between tumor necrosis factor (TNF) and HLA-B in the central major histocompatibility complex (MHC) is polymorphic and associated with several autoimmune diseases. The polymorphisms are haplospecific or haplotypic and retained within the same MHC ancestral haplotype (AH). We have cloned this region from four AHs into λ bacteriophage and found that a highly polymorphic region in the TNF-HLA-B interval is duplicated. Clones from this region isolated from three MHC AHs show two populations. The regions, designated CL1 and CL2, have different sizes of Bam HI fragments carrying the duplicated sequences. These fragments correspond to those seen after Bam HI restriction fragment length polymorphism (RFLP) analysis of genomic DNA from the same cell lines. Pulsed field gel electrophoresis analysis shows that both CL1 and CL2 are in the central MHC and are about 16 kilobases apart. DNA cloning and RFLP analysis demostrate that the Cl region is highly polymorphic but retained within an MHC AH. Polymorphism and duplication are common characteristics of the genes found in the MHC and therefore the CL sequences have the potential to be interesting in this respect.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 1432-1211
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We have used genomic analysis to characterize a region of the central major histocompatibility complex (MHC) spanning ∼ 300 kilobases (kb) betweenTNF andHLA-B. This region has been suggested to carry genetic factors relevant to the development of autoimmune diseases such as myasthenia gravis (MG) and insulin dependent diabetes mellitus (IDDM). Genomic sequence was analyzed for coding potential, using two neural network programs, GRAIL and GeneParser. A genomic probe, JAB, containing putative coding sequences (PERB11) located 60 kb centromeric ofHLA-B, was used for northern analysis of human tissues. Multiple transcripts were detected. Southern analysis of genomic DNA and overlapping YAC clones, covering the region fromBAT1 toHLA-F, indicated that there are at least five copies of PERB11, four of which are located within this region of the MHC. The partial cDNA sequence ofPERB11 was obtained from poly-A RNA derived from skeletal muscle. The putative amino acid sequence ofPERB11 shares ∼ 30%o identity to MHC class I molecules from various species, including reptiles, chickens, and frogs, as well as to other MHC class I-like molecules, such as the IgG FeR of the mouse and rat and the human Zn-α2-glycoprotein. From direct comparison of amino acid sequences, it is concluded thatPERB11 is a distinct molecule more closely related to nonmammalian than known mammalian MHC class I molecules. Genomic sequence analysis ofPERB11 from five MHC ancestral haplotypes (AH) indicated that the gene is polymorphic at both DNA and protein level. The results suggest thet we have identified a novel polymorphic gene family with multiple copies within the MHC.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    ISSN: 1600-065X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Summary: The genomic region encompassing the Major Histocompatibility Complex (MHC) contains polymorphic frozen blocks which have developed by local imperfect sequential duplication associated with insertion and deletion (indels), In the alpha block surrounding HLA-A, there are ten duplication units or beads on the 62,1 ancestral haplotype. Each bead contains or contained sequences representing Class 1, PERB11 (MHC Class I chain related (MIC)) and human endogenous retrovirus (HERV) 16, Here we consider explanations for co-occurrence of genomic polymorphism, duplication and HERVs and we ask how these features encode susceptibility to numerous and very diverse diseases. Ancestral haplotypes differ in their copy number and indels in addition to their coding regions. Disease susceptibility could be a function of all of these differences. We propose a model of the evolution of the human MHC. Population-specific integration of retroviral sequences could explain rapid diversification through duplication and differential disease susceptibility. If HERV sequences can be protective, there are exciting prospects for manipulation. In the mean-while, it will be necessary to understand the function of MHC genes such as PEKB11 (MIC) and many others discovered by genomic sequencing.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    ISSN: 1365-4632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background  To evaluate the distributions of the human leukocyte antigen (HLA) at class I and II loci that may contribute to the genetic susceptibility to psoriasis patients in the north-eastern Thai population.Materials and methods  We analyzed the allelic frequencies of HLA class I and II by using the polymerase chain reaction-amplification refractory mutation system (PCR-ARMS) technique and polymerase chain reaction-single stranded conformation polymorphism (PCR-SSCP), respectively, in 140 north-eastern Thais with psoriasis that were sudivided into two groups: one with age at onset 〈 40 years (type I psoriasis; 95 cases) and the other with age at onset 〉 40 years (type II psoriasis; 45 cases). Three hundred healthy unrelated north-eastern Thais were used as controls.Results  HLA-A*01, -A*0207, -A*30, -B*08, -B*13, -B*4601, -B*57, -Cw*01, -Cw*0602, and -DRB1*07 were positively associated with type I psoriasis, whereas HLA-A*24, -A*33, and -Cw*04 were negatively associated with type I psoriasis with statistical significance when compared to the controls. The Cw*0602 allele showed the strongest correlation with this type. In addition, the frequencies of HLA-A*0207, -A*30, -Cw*01, and -DRB1*1401 were significantly increased in type II psoriasis. HLA-A*207, -B*4601, -Cw*01, -DRB1*09, -DQB1*0303 (AH46.1), HLA-A*01-B*57-Cw*0602-DRB1*07-DQB1*0303 (AH57.1), and HLA-A*30, -B*13, -Cw*0602, -DRB1*07, and -DQB1*02 (AH13.1) were identified as high-risk major histocompatibility complex (MHC) halotypes for psoriasis patients in the early onset group in north-eastern Thais.Conclusions  This study demonstrates not only the differential association between HLA markers and types of psoriasis according to age at onset, but also a newly found high-risk and a protective haplotype in Thai psoriasis patients.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    ISSN: 1432-1432
    Keywords: Key words: PERB11.1 — MICA — Nomenclature — Putative lineage — Polymorphism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. Several highly polymorphic sequences are present in the beta block of the MHC, especially HLA-B, HLA-C, PERB11.1 (MICA), and PERB11.2 (MICB). It is now apparent that the polymorphism of PERB11.1 is of the same order as that of HLA-A, -B, and -C and it has been suggested that PERB11 could explain some of the disease associations previously attributed to HLA-B. Phylogenetic analysis of PERB11 α-domain sequences demonstrates relationships with HLA-B cross-reactive serogroups. In contrast, the transmembrane polymorphisms do not appear to be associated with either PERB11 or HLA-B. These data indicate that PERB11 and HLA-B have evolved in concert from their common ancestors and that the transmembrane polymorphisms have arisen independently and more recently. MHC disease associations will need to be reviewed in the light of mechanisms such as receptor binding and signaling.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...