Add biomarker class
Not sure if we already have this. We want to be able to say that certain substances or tests serve as biomarkers. There are a few biomarker classes in OLS (https://www.ebi.ac.uk/ols/search?q=biomarker) but I'm not sure any of them are ideal. Is biomarker a role?
Use case: https://c-path.org/programs/bmdr/