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Variation Ontology, VariO, is an ontology for standardized, systematic description of effects, consequences and mechanisms of variations. VariO allows unambiguous description of variation effects as well as computerized analyses over databases utilizing the ontology for annotation. VariO is a position specific ontology that can be used to describe effects of variations on DNA, RNA and/or protein level, whatever is appropriate.

VariO allows

consistent naming
annotation of variation effects
data integration
comparison of variations and datasets
statistical studies
development of sofware tools

The VariO ontology can be viewed using an ontology editor, such as OBO-Edit.
VariO is available in OBO, OWL and OWX formats here.


  • Vihinen, M., 2014. Variation Ontology for annotation of variation effects and mechanisms.
    Genome Res. 24:356-364   PUBMED  
  • Vihinen, M., 2014. Variation ontology: annotator guide. J Biomed Semantics 5:9   PUBMED  
  • Vihinen, M., 2015. Types and effects of protein variations. Hum Genet. 134:405-421   PUBMED  

Examples of how to use VariO for annotation of variants on protein level can be found here. Examples for the annotation of variants on DNA and RNA levels be available later.

VariO is available and linked via several services including:

Last updated 2018-08-03 by Gerard Schaafsma