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<article xmlns:xlink="http://www.w3.org/1999/xlink">
  <front>
    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>DisGeNET RDF: a gene-disease association Linked Open Data resource</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Nuria Queralt-Rosinach</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Laura I. Furlong</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Research Programme on Biomedical Informatics (GRIB), Hospital del Mar Medical Research Institute (IMIM), Pompeu Fabra University (UPF)</institution>
          ,
          <addr-line>C/ Dr. Aiguader 88, 08003 Barcelona</addr-line>
          ,
          <country country="ES">Spain</country>
        </aff>
      </contrib-group>
      <abstract>
        <p>We present the rst RDF representation of DisGeNET, a gene-disease database designed to integrate the current knowledge of human diseases. DisGeNET RDF data introduces a harmonized and semantically enriched description of the gene-disease association concept into the Semantic Web (SW) by means of the DisGeNET ontology. The centric view on gene-disease associations allows to nd links between diseases and genes easily and with added semantic content. The RDF representation follows the Linked Data (LD) principles that provides new opportunities for data integration, querying and crossing DisGeNET data with other external RDF datasets. The RDF version of DisGeNET has been developed in the context of the Open PHACTS project to provide disease relevant information to the knowledge base on pharmacological data.</p>
      </abstract>
      <kwd-group>
        <kwd>gene-disease association</kwd>
        <kwd>RDF</kwd>
        <kwd>ontology</kwd>
        <kwd>linked data</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>-</title>
      <p>
        DisGeNET RDF is presented as a new resource in the Linked Open Data space
to promote the discovery of key knowledge in the understanding of the
molecular mechanisms underlying a disease or an adverse drug event. DisGeNET [
        <xref ref-type="bibr" rid="ref1 ref2">1,
2</xref>
        ] is a relational database that integrates gene-disease associations from curated
databases and the literature, and additional information such as pathways or
SNPs. DisGeNET has been mapped to RDF using the most advanced Semantic
Web technologies such as OWL and SPARQL. In this workshop, we are
introducing DisGeNET as a new RDF resource in the LD space, the methodology
used for its conversion, the speci c ontology developed to model the gene-disease
association concept and, nally, some potential applications of the resource.
2.1
      </p>
    </sec>
    <sec id="sec-2">
      <title>Methodology</title>
      <sec id="sec-2-1">
        <title>The RDF Schema, ontologies and identi ers</title>
        <p>
          The RDF version of DisGeNET is represented as a set of triples around the
gene-disease association concept. Information such as genomic variation or
scienti c publications supporting the association are related to this main
concept. Data is organized in a hierarchical manner around ve concepts: gene,
disease, pathway, disease class, and gene-disease association as the parent
concept (see DisGeNET RDF web interface http://rdf.imim.es/DisGeNET.html
for details on the RDF schema). The `RDF-ization' has been done using RDFS
and OWL languages, common ontologies and vocabularies, and following the
Linked Data principles (http://linkeddata.org/). To identify resources in
DisGeNET, URIs established by the identi ers.org e ort were selected
whenever possible to support its initiative to foster a uni ed use of URIs by the SW
community [
          <xref ref-type="bibr" rid="ref3">3</xref>
          ]. DisGeNET data is open and is linked out to other linked data
resources such as Linked Life Data (http://linkedlifedata.com/) or Bio2RDF
projects [
          <xref ref-type="bibr" rid="ref4">4</xref>
          ].
2.2
        </p>
      </sec>
      <sec id="sec-2-2">
        <title>DisGeNET gene-disease association ontology</title>
        <p>
          The DisGeNET gene-disease association ontology harmonizes the semantic
description of the di erent types of associations between genes and diseases. The
ontology provides foundational support for the DisGeNET database. This
ontology was integrated in the increasingly used Semanticscience Integrated Ontology
(SIO) [
          <xref ref-type="bibr" rid="ref5">5</xref>
          ], which is an ontology meant to be adopted to describe basic scienti c
semantics and ensure correct concept mapping among other more speci c
ontologies. The DisGeNET ontology can be accessed at http://ibi.imim.es/
DisGeNET-Dev/ontologies/GeneDiseaseAssociation.owl.
2.3
        </p>
      </sec>
      <sec id="sec-2-3">
        <title>Provenance description</title>
        <p>
          It is considered good practice to provide provenance information to an RDF
resource. The provenance description of the DisGeNET RDF dataset declares
the database from which it is derived, the development date, the current version
and updates, the software used for its development, the license information,
the SPARQL endpoint location, the number of triples, etc... The provenance
description of the original database and each primary source is also tracked. This
information is provided using the Vocabulary of Interlinked Datasets (VoID) [
          <xref ref-type="bibr" rid="ref6">6</xref>
          ].
2.4
        </p>
      </sec>
      <sec id="sec-2-4">
        <title>Data processing</title>
        <p>
          To map the relational database content into RDF triples, we used the D2RQ
platform (http://d2rq.org/). The dump les and the VoID description of
DisGeNET are loaded into the OpenLink Virtuoso RDF Quad Store [
          <xref ref-type="bibr" rid="ref7">7</xref>
          ]. An
SPARQL endpoint hosted in the Virtuoso server has been implemented as the
primary interface to access the RDF data (for access to RDF data see the
DisGeNET RDF web interface). Validation of data was done with Protege platform
(http://protege.standford.edu) and our SPARQL endpoint.
        </p>
        <p>DisGeNET RDF: a new member in the LD community</p>
      </sec>
    </sec>
    <sec id="sec-3">
      <title>Results: Integration across resources</title>
      <p>We present the potential of DisGeNET Linked Data with di erent uses cases.
The rst use case is aimed at answering the following question: give me all
the gene-disease associations from the Comparative Toxicogenomics Database
(CTD) that have information on sequence variation and provenance. This
question can be answered exploiting the information contained in DisGeNET,
selecting the associations provided by CTD and that have annotations on genomic
variation and literature provenance. This is translated in the following SPARQL
query:
SELECT DISTINCT ?gdassocIRI ?dName ?gName ?snpLabel ?PMIDLabel
WHERE
{
}
?gdassocIRI sio:SIO_000628 ?disease,?gene .
?disease rdf:type ncit:C7057 .
?disease foaf:name ?dName .
?gene rdf:type ncit:C16612 .
?gene sio:SIO_000205 ?genenameURI .
?genenameURI rdfs:label ?gName .
?gdassocIRI sio:SIO_000001 ?snp .
?snp rdf:type ncit:C18279 .
?snp rdfs:label ?snpLabel .
?gdassocIRI sio:SIO_000253 ?source .</p>
      <p>FILTER regex(?source,"ctd")
?gdassocIRI sio:SIO_000772 ?PubMedID .</p>
      <p>?PubMedID rdfs:label ?PMIDLabel .</p>
      <p>
        The inclusion of DisGeNET into the 'Web of linked data' using the most
advanced SW technologies brings the opportunity to integrate our gene-disease
data with other disparate data sources spread over the Web by performing
federated queries. The second use case is aimed at answering the following question:
give me all the gene-disease associations in which the association is linked to
changes in the expression of the gene, there is expression information, and
sequence variation linked to the disease. This question can be answered by querying
and integrating data from DisGeNET and GXA (http://www.ebi.ac.uk/gxa/)
databases. More speci cally, we ask for the DisGeNET gene-disease associations
labelled as 'AlteredExpression' and their related SNPs, and the GXA expression
values. See the SPARQL query at the DisGeNET RDF web interface. DisGeNET
SPARQL endpoint supports the syntax and semantics of SPARQL 1.1 for
executing queries distributed over di erent SPARQL endpoints. SPARQL queries
such these are aimed to be included in Bioqueries which is a portal aimed at
gathering SPARQL queries [
        <xref ref-type="bibr" rid="ref8">8</xref>
        ].
      </p>
      <p>As the last use case, DisGeNET RDF has been implemented in the Open
Pharmacological Space (OPS) discovery platform, which is a SW platform
developed under the Innovative Medicines Initiative (IMI; http://www.imi.europa.
eu) funded Open PHACTS project. Remarkably, the integration of DisGeNET
in OPS is essential to answer important research questions such as which
compounds could e ectively inhibit targets involved in a key pathway for the
development of a disease. Aimed at exploring and querying DisGeNET data across
the linked data in the platform, APIs are currently under development (see the
API website for up to date information at http://dev.openphacts.org). This
is expected to be fully operative in the upcoming OPS 1.5 release.
4</p>
    </sec>
    <sec id="sec-4">
      <title>Conclusions</title>
      <p>We present DisGeNET RDF, a new Linked Data dataset that provides
genedisease association data to answer relevant scienti c pharmacological complex
questions. Importantly, DisGeNET has been implemented in the
pharmacological LD discovery platform developed within the Open PHACTS project.
Acknowledgments. The research leading to these results has received
support from the IMI Joint Undertaking under grant agreement n 115191, Open
PHACTS, resources of which are composed of nancial contribution from the
EU FP7 (FP7/2007-2013) and EFPIA companies' in kind contribution; and the
Instituto de Salud Carlos III FEDER (CP10/005249). The Research Programme
on Biomedical Informatics (GRIB) is a node of the Spanish National Institute
of Bioinformatics (INB).</p>
    </sec>
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