Indirect associations between targets and diseases are computed based on indirect evidence, rather than observed (direct) evidence.
If you search for a target using the web interface of the Open Targets Platform, you will get associations based on direct evidence only. However, if you search for a disease, you will get both direct and indirect associations, since we propagate evidence from lower sections of a disease ontology, this evidence is used as indirect evidence for the associations.
When retrieving our data via the Open Targets REST API, you will get two types of association counts:
The difference between
directis the number of associations based on indirect evidence.
To get direct associations only, you should include the parameter
direct = true when using our REST-API endpoints, such as the
We propagate the indirect evidence from a child term up to its parent term in the disease ontology for all diseases in our Platform. By computing new target-disease associations when there is no direct (known and observed) evidence for them, we allow:
finding common targets across groups of related diseases (e.g. ulcerative colitis, Crohn's disease and inflammatory bowel disease)
making connections between rare and common diseases (e.g. autosomal recessive early-onset inflammatory bowel disease and inflammatory bowel disease)
grouping evidence for all diseases within a therapeutic area
identifying unforeseen associations by serendipity