51 research outputs found

    On HIRA, Chromosome 22q11 and CATCH22

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    On HIRA, Chromosome 22q11 and CATCH22

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    Dynamic instability of the major urinary protein gene family revealed by genomic and phenotypic comparisons between C57 and 129 strain mice

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    Targeted sequencing, manual genome annotation, phylogenetic analysis and mass spectrometry were used to characterise major urinary proteins (MUPs) and the Mup clusters of two strains of inbred mice

    Positional mapping of loci in the DiGeorge critical region at chromosome 22q11 using a new marker (D22S183)

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    The majority of patients with DiGeorge syndrome (DGS) and velo-cardio-facial syndrome (VCFS) and a minority of patients with non-syndromic conotruncal heart defects are hemizygous for a region of chromosome 22q11. The chromosomal region that is commonly deleted is larger than 2 Mb. It has not been possible to narrow the smallest region of overlap (SRO) of the deletions to less than ca 500 kb, which suggests that DGS/VCFS might be a contiguous gene syndrome. The saturation cloning of the SRO is being carried out, and one gene (TUPLE1) has been identified. By using a cosmid probe (M51) and fluorescence in situ hybridization, we show here that the anonymous DNA marker locus D22S183 is within the SRO, between TUPLE1 and D22S75 (probe N25). A second locus with weak homology to D22S183, recognized by cosmid M56, lies immediately outside the common SRO of the DGS and VCFS deletions, but inside the SRO of the DGS deletions. D22S183 sequences are strongly conserved in primates and weaker hybridizing signals are found in DNA of other mammalian species; no transcripts are however detected in polyA+ RNA from various adult human organs. Probe M51 allows fast reliable screening for 22q11 deletions using fluorescence in situ hybridization. A deletion was found in 11 out of 12 DGS patients and in 3 out of 7 VCFS patients. Two patients inherited the deletion from a parent with mild (atypical) symptoms

    Pseudo–Messenger RNA: Phantoms of the Transcriptome

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    The mammalian transcriptome harbours shadowy entities that resist classification and analysis. In analogy with pseudogenes, we define pseudo–messenger RNA to be RNA molecules that resemble protein-coding mRNA, but cannot encode full-length proteins owing to disruptions of the reading frame. Using a rigorous computational pipeline, which rules out sequencing errors, we identify 10,679 pseudo–messenger RNAs (approximately half of which are transposon-associated) among the 102,801 FANTOM3 mouse cDNAs: just over 10% of the FANTOM3 transcriptome. These comprise not only transcribed pseudogenes, but also disrupted splice variants of otherwise protein-coding genes. Some may encode truncated proteins, only a minority of which appear subject to nonsense-mediated decay. The presence of an excess of transcripts whose only disruptions are opal stop codons suggests that there are more selenoproteins than currently estimated. We also describe compensatory frameshifts, where a segment of the gene has changed frame but remains translatable. In summary, we survey a large class of non-standard but potentially functional transcripts that are likely to encode genetic information and effect biological processes in novel ways. Many of these transcripts do not correspond cleanly to any identifiable object in the genome, implying fundamental limits to the goal of annotating all functional elements at the genome sequence level

    The role of Havana and communities in the manual curation of unfinished vertebrate genomes

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    Manual annotation‭ (‬the‭ "‬museum‭" ‬model of annotation‭) ‬relies on a small group of specialized curators to catalogue and classify genes according to their functional roles.‭ This‬ is both costly and time consuming and therefore is used only for model organisms with sufficient funding.‭ ‬Smaller research communities often have to rely on other models of annotation,‭ ‬mainly automated annotation‭ (‬the‭ "‬factory‭" ‬model,‭ ‬e.g.‭ ‬Ensembl‭)‬,‭ ‬and the‭ "‬jamboree‭" ‬model‭ (‬in which a group of leading biologists from the community and bioinformaticians come together for a short intensive annotation workshop‭)‬.‭ ‬At the Wellcome Trust Sanger Institute‭ (‬WTSI‭)‬,‭ ‬the Havana team provides high quality manual annotation of finished vertebrate genome sequences,‭ ‬namely human,‭ ‬mouse and zebrafish.‭ ‬We also perform the curation of specific finished regions such as the MHC in dog,‭ ‬cow and pig,‭ ‬whose whole genomes have been‭ ‬assembled from unfinished BACs or from whole genome shotgun sequences.‭ ‬In addition,‭ ‬we at Havana have also hosted annotation jamborees for the cow‭ (‬Bos taurus‭) ‬and pig‭ (‬Sus scrofa‭) ‬genomes.‭ ‬During those sessions,‭ ‬the research community had the opportunity to annotate their genes of interest under expert guidance using the custom written publicly available Otterlace annotation system,‭ ‬and the unified manual annotation guidelines.‭ ‬By making use of the tools and skills acquired during the cow and pig jamborees,‭ ‬the delegates can continue annotating their genomes remotely.‭ ‬For the pig genome,‭ ‬a highly contiguous physical map has been generated by an international effort of four laboratories (available in Pre!Ensembl) and‭ ‬is being used as a substrate for the swine genome sequencing project.‭ ‬Upcoming vertebrate genomes will be sequenced to a high depth coverage with the next generation sequencing technologies‭ (‬e.g.‭ ‬Illumina,‭ ‬454,‭ ‬SOLiD‭) ‬but will have the drawback of not being manually finished.‭ ‬Manual annotation will be more accurate than the automated predictions at coping with any assembly problems derived from these high coverage but unfinished‭ (‬or automatic pre-finished‭) ‬genomes.‭ ‬Once these inherent assembly errors are corrected and the gene structures are accurately identified with manual annotation,‭ ‬the curated genes will be incorporated and merged with the predicted gene models in Ensembl to provide a unified view of the landscape of vertebrate genomes.‭ ‬I will present an introduction to our manual annotation system and our experience using it for annotation jamborees at the WTSI

    Harmonizing model organism data in the Alliance of Genome Resources.

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    The Alliance of Genome Resources (the Alliance) is a combined effort of 7 knowledgebase projects: Saccharomyces Genome Database, WormBase, FlyBase, Mouse Genome Database, the Zebrafish Information Network, Rat Genome Database, and the Gene Ontology Resource. The Alliance seeks to provide several benefits: better service to the various communities served by these projects; a harmonized view of data for all biomedical researchers, bioinformaticians, clinicians, and students; and a more sustainable infrastructure. The Alliance has harmonized cross-organism data to provide useful comparative views of gene function, gene expression, and human disease relevance. The basis of the comparative views is shared calls of orthology relationships and the use of common ontologies. The key types of data are alleles and variants, gene function based on gene ontology annotations, phenotypes, association to human disease, gene expression, protein-protein and genetic interactions, and participation in pathways. The information is presented on uniform gene pages that allow facile summarization of information about each gene in each of the 7 organisms covered (budding yeast, roundworm Caenorhabditis elegans, fruit fly, house mouse, zebrafish, brown rat, and human). The harmonized knowledge is freely available on the alliancegenome.org portal, as downloadable files, and by APIs. We expect other existing and emerging knowledge bases to join in the effort to provide the union of useful data and features that each knowledge base currently provides

    Genetic Analysis of Completely Sequenced Disease-Associated MHC Haplotypes Identifies Shuffling of Segments in Recent Human History

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    The major histocompatibility complex (MHC) is recognised as one of the most important genetic regions in relation to common human disease. Advancement in identification of MHC genes that confer susceptibility to disease requires greater knowledge of sequence variation across the complex. Highly duplicated and polymorphic regions of the human genome such as the MHC are, however, somewhat refractory to some whole-genome analysis methods. To address this issue, we are employing a bacterial artificial chromosome (BAC) cloning strategy to sequence entire MHC haplotypes from consanguineous cell lines as part of the MHC Haplotype Project. Here we present 4.25 Mb of the human haplotype QBL (HLA-A26-B18-Cw5-DR3-DQ2) and compare it with the MHC reference haplotype and with a second haplotype, COX (HLA-A1-B8-Cw7-DR3-DQ2), that shares the same HLA-DRB1, -DQA1, and -DQB1 alleles. We have defined the complete gene, splice variant, and sequence variation contents of all three haplotypes, comprising over 259 annotated loci and over 20,000 single nucleotide polymorphisms (SNPs). Certain coding sequences vary significantly between different haplotypes, making them candidates for functional and disease-association studies. Analysis of the two DR3 haplotypes allowed delineation of the shared sequence between two HLA class II–related haplotypes differing in disease associations and the identification of at least one of the sites that mediated the original recombination event. The levels of variation across the MHC were similar to those seen for other HLA-disparate haplotypes, except for a 158-kb segment that contained the HLA-DRB1, -DQA1, and -DQB1 genes and showed very limited polymorphism compatible with identity-by-descent and relatively recent common ancestry (<3,400 generations). These results indicate that the differential disease associations of these two DR3 haplotypes are due to sequence variation outside this central 158-kb segment, and that shuffling of ancestral blocks via recombination is a potential mechanism whereby certain DR–DQ allelic combinations, which presumably have favoured immunological functions, can spread across haplotypes and populations

    Discovery of candidate disease genes in ENU-induced mouse mutants by large-scale sequencing, including a splice-site mutation in nucleoredoxin.

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    An accurate and precisely annotated genome assembly is a fundamental requirement for functional genomic analysis. Here, the complete DNA sequence and gene annotation of mouse Chromosome 11 was used to test the efficacy of large-scale sequencing for mutation identification. We re-sequenced the 14,000 annotated exons and boundaries from over 900 genes in 41 recessive mutant mouse lines that were isolated in an N-ethyl-N-nitrosourea (ENU) mutation screen targeted to mouse Chromosome 11. Fifty-nine sequence variants were identified in 55 genes from 31 mutant lines. 39% of the lesions lie in coding sequences and create primarily missense mutations. The other 61% lie in noncoding regions, many of them in highly conserved sequences. A lesion in the perinatal lethal line l11Jus13 alters a consensus splice site of nucleoredoxin (Nxn), inserting 10 amino acids into the resulting protein. We conclude that point mutations can be accurately and sensitively recovered by large-scale sequencing, and that conserved noncoding regions should be included for disease mutation identification. Only seven of the candidate genes we report have been previously targeted by mutation in mice or rats, showing that despite ongoing efforts to functionally annotate genes in the mammalian genome, an enormous gap remains between phenotype and function. Our data show that the classical positional mapping approach of disease mutation identification can be extended to large target regions using high-throughput sequencing

    The Consensus Coding Sequence (Ccds) Project: Identifying a Common Protein-Coding Gene Set for the Human and Mouse Genomes

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    Effective use of the human and mouse genomes requires reliable identification of genes and their products. Although multiple public resources provide annotation, different methods are used that can result in similar but not identical representation of genes, transcripts, and proteins. The collaborative consensus coding sequence (CCDS) project tracks identical protein annotations on the reference mouse and human genomes with a stable identifier (CCDS ID), and ensures that they are consistently represented on the NCBI, Ensembl, and UCSC Genome Browsers. Importantly, the project coordinates on manually reviewing inconsistent protein annotations between sites, as well as annotations for which new evidence suggests a revision is needed, to progressively converge on a complete protein-coding set for the human and mouse reference genomes, while maintaining a high standard of reliability and biological accuracy. To date, the project has identified 20,159 human and 17,707 mouse consensus coding regions from 17,052 human and 16,893 mouse genes. Three evaluation methods indicate that the entries in the CCDS set are highly likely to represent real proteins, more so than annotations from contributing groups not included in CCDS. The CCDS database thus centralizes the function of identifying well-supported, identically-annotated, protein-coding regions.National Human Genome Research Institute (U.S.) (Grant number 1U54HG004555-01)Wellcome Trust (London, England) (Grant number WT062023)Wellcome Trust (London, England) (Grant number WT077198
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