Effect is a type of Validity. Effect is related to Disease. Stroke is a type of Disease. 
Icon is a type of Symbol. Icon is related to Cross. Cross is related to Distinguish. Characterize is a type of Distinguish. 
Validity <--IsA-- Effect <--RelatedTo--> Disease <--IsA-- Stroke 
Symbol <--IsA-- Icon <--RelatedTo--> Cross <--RelatedTo--> Distinguish <--IsA-- Characterize 