indicates response to Clarification: An 'exposure agent' can be either a medical product or some substance (e.g., pesticide) , physical factor (e.g., radiation), or organism (e.g., virus) that originates from the environment. Basis: This relation is based on the 'BEST' classification of and definition for 'biomarker', as given by the FDA-NIH Biomarker Working Group: A defined characteristic that is measured as an indicator of normal biological processes, pathogenic processes, or biological responses to an exposure or intervention, including therapeutic interventions. The BEST classification includes diagnostic, prognostic, susceptibility/risk, monitoring, predictive, safety, and pharmacodynamic/response biomarkers. See PMID:29405771 for details. Note that any given biomarker can be of a different type in different contexts. A relationship between a biomarker 'b' and an exposure agent 'e', where 'b' is used to show that a biological response to 'e' has occurred. https://orcid.org/0000-0001-5809-9523 The level of urinary glycosaminoglycans indicates_response_to enzyme replacement therapy for patients with mucopolysaccharidosis type 1. indicates clinical effect of Darren A. Natale