Syndrome is related to Fatigue. Fatigue is related to Chronic. Chronic is a synonym of Continuing. Continuing is similar to Continued. 
Underlying is related to Structure. Passage is a type of Structure. Passage is a synonym of Travel. Wheel is a type of Travel. 
Syndrome <--RelatedTo--> Fatigue <--RelatedTo--> Chronic <--Synonym--> Continuing <--SimilarTo--> Continued 
Underlying <--RelatedTo--> Structure <--IsA-- Passage <--Synonym--> Travel <--IsA-- Wheel 