The Biosemantics group at the Erasmus MC followed a thesaurus-based approach for the first task of the genomics track. The approach is based on a concept-based indexing engine (Collexis®), suitable for large cale and high-speed indexing. The thesaurus used for indexing was constructed as a combination of the MESH thesaurus and the gene ontology (GO), with a species-specific gene thesaurus derived from LocusLink gene annotations. Our indexing machinery produces per indexed MEDLINE abstract a list of concepts with an accompanying weight, termed a fingerprint. Searching is done by matching a query fingerprint against fingerprints of all indexed MEDLINE abstracts. Query fingerprints are generated by combining fingerprints of four types. First, a fingerprint containing just the gene concept with all the known gene names and aliases. Second, a combination of MEDLINE fingerprints of all abstracts in which the gene concept was found without ambiguity problems. Third, a generic fingerprint with concepts typical of geneRIFs, when compared to MEDLINE in general. Fourth, a fingerprint containing the concepts of the Gene Ontology (GO) annotation