2018
Leukopenia due to parvovirus B19 in a Crohn 's disease patient using azathioprine .
 Leukopenia, azathioprine
Please list all entity pairs containing a certain relationship in the given options.Output format is "word1, word2; word3, word4". 
Option: adverse effect 
Text: {0} 
Answer:
 Leukopenia, azathioprine