1721
Studies of these females show that the XIST locus on their tiny ring X chromosomes is either not present or not expressed.
 ( DNA: XIST locus, None) , ( DNA: X chromosomes, None) , ( DNA: tiny ring X chromosomes, None) 
Locate the role in the text that participated in the event based on the event type and return it in the event list. 
 Option: Event type: RNA,cell type,protein,cell line,DNA, Arguments type: . 
Text: {0} 
Answer:
 ( DNA: XIST locus, None) , ( DNA: X chromosomes, None) , ( DNA: tiny ring X chromosomes, None) 